WASHINGTON -- It was one of the worst days D.C. has seen in a long time.

Twelve people were killed and 14 others were wounded at the Navy Yard on Monday after a gunman police identified as Aaron Alexis opened fire on employees in one of the buildings.

Police later killed Alexis, but officers remained on high alert all day as a second possible shooter was reported at large. Roads were closed for blocks. Businesses shut down. People in nearby buildings were instructed to stay inside. The Senate went into shutdown mode, planes at nearby airports were grounded, and the Nationals, whose baseball stadium is blocks from the Navy Yard, called off their scheduled evening game against the Braves.

By Monday evening, it was still unclear whether there had been a second shooter. Navy Yard employees -- there are roughly 3,000 of them -- were allowed to leave the complex by 3:30 p.m., having been on lockdown for hours. And slowly, hundreds began to fill the empty streets and make their way to the nearby Metro station. Some stopped for a few minutes to talk to reporters about their experience.

"Terrifying," said Gregory Dade, who said he locked himself in his office as gunfire carried on for nearly an hour outside his door.

"There were several shots. Rapid shots, single shots. One young lady screamed out, 'Help! Help!'" Dade said. "We thought maybe it calmed down, but then you'd hear it again. Somebody yelling, glass breaking. ... Then you'd hear some single shots, some more rapid fire. ... We didn't know who was running up and down the hallway."

Dade, a Hewlett Packard technician who has worked with Navy Yard employees for nearly 10 years, said some of the victims were his close friends.

"I've heard ... several of my friends I've been working with were shot," he said. "Some of the names I've heard ... I hope they're okay."

Navy Commander Tim Jirus said he heard what sounded like a cap gun going off a few times, and didn't think much of it. But minutes later, he was outside the building in an alley running for his life as a colleague he had just been talking to was shot in the head.

"He dropped in front of me," Jirus said. "I took off after that."

Jirus, who's been in the Navy for 25 years, said he's used to training for combat operations overseas and has seen dead people before. Monday's shootings were different, he said.

"Seeing somebody die in front of you, here where you work at, is more of a relationship of you talking to God or you realizing just how fragile life is," Jirus said. "To hear gunshots and realize you were that close to being shot, it makes me like life a lot today. I'm going to hug my kids the next time I see them and have a good day."

Swarms of reporters were at the scene for throughout the day and into the evening. D.C. Mayor Vincent Gray came by and gave updates at a couple of quick press conferences, along with D.C. Police Chief Cathy Lanier. D.C. Del. Eleanor Holmes Norton also spoke to the press.

Anyone in need of a bite to eat had limited choices. Most area restaurants closed. Some had handwritten signs taped to front doors citing the shooting. One Subway stayed open, so it quickly became a hot spot for reporters desperate to recharge their computers.

With police cars everywhere and so many streets roped off, some employees of nearby businesses were perplexed at how to get home Monday evening.

"Damn ... What? ... Well hell, how we gonna get out of our parking lot?" one woman asked another as they left their building.

City officials helped remedy the situation by bringing in special buses to shuttle Navy Yard employees out of the area. A D.C. Metro police officer told HuffPost that all Navy Yard employees would get a free ride home on Metro for the night.

Dade was among those nabbing a Metro ride home. He was heading into the Navy Yard Metro station when he stopped briefly to talk to reporters.

"Folks, I'm tired," he finally said with a weak smile. "I've been in since 5:30 this morning. I want to go home."

Here are some photos from the day's events outside the Navy Yard on Monday:

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navy yard shootings

navy yard shootings

navy yard shootings

navy yard shootings

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  • Navy Yard Shooter Alleged Suspect Aaron Alexis

    UNKNOWN, UNSPECIFIED - SEPTEMBER 16: In this handout photo provided by the FBI, Aaron Alexis is shown in a photo prior to the mass shooting at the Washington Navy Yard on September 16, 2013 in Washington, D.C. Authorities believe Alexis was a gunman involved in the shootings at the Navy Yard, where at least 12 people were shot and killed. (Photo by FBI via Getty Images)

  • Family and friends wait to greet staff of the Naval Sea Systems Command headquarters as they are bused from the Washington Navy Yard to Nationals Park, in Washington, Monday, Sept. 16, 2013. At least one gunman launched an attack inside the Washington Navy Yard, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital, authorities said. (AP Photo/Jacquelyn Martin)

  • US-MILITARY-SHOOTING

    Police conduct an investigation into a shooting at the Navy Yard in Washington, DC, September 16, 2013. A shooting rampage Monday at a US naval base in the heart of Washington claimed at least 13 lives, including the unidentified gunman, while another possible suspect was still at large, police said. The shooting sparked a massive show of force as police and federal agents surrounded the Navy Yard, cordoning off streets only blocks from the US Capitol, home of Congress. US officials gave no indication of any link to terrorism while police said the motive for the attack on the naval installation was unknown. 'At this hour, it appears that we have at least 12 fatalities,' Washington DC police chief Cathy Lanier told a press conference. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • Nii Oti-Ankrah, left, kisses his wife Sally Appiah-Ankrah as he holds their son Eilam Ankrah after she was evacuated from building 197 at the Washington Navy Yard, Monday Sept. 16, 2013 in Washington. At least one gunman launched an attack inside the Washington Navy Yard, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital, authorities said. (AP Photo/Alex Brandon)

  • An officer who said he works for the Department of Defense, right, checks an id outside of the closed Washington Navy Yard in Washington, on Tuesday, Sept. 17, 2013, the day after a gunman launched an attack inside the Washington Navy Yard on Monday, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital. Only essential personnel were being permitted inside, according the authorities. (AP Photo/Jacquelyn Martin)

  • Shooting At Washington DC Navy Yard Reportedly Leaves Several Wounded

    WASHINGTON, DC - SEPTEMBER 16: Family members of Navy Yard complex employees gather outside a parking lot that was converted to a point of reunion at Nationals Park in the wake of the Navy Yard shooting September 16, 2013 in Washington, DC. Police believe at least one gunman shot and killed 12 people and wounded others in an incident that put parts of the city on lockdown. (Photo by Win McNamee/Getty Images)

  • Shooting At Washington DC Navy Yard Reportedly Leaves Several Wounded

    WASHINGTON, DC - SEPTEMBER 16: A woman hugs her child while reuniting at a gathering point for family members of Navy Yard employees that was set up inside Nationals Park in the wake of the shooting September 16, 2013 in Washington, DC. Police believe at least one gunman shot and killed at least 12 people and wounded others in an incident that put parts of the city on lockdown. (Photo by Win McNamee/Getty Images)

  • US-MILITARY-SHOOTING

    A Red Cross vehicle arrives at a family gathering point for the Navy Yard shootings set up at parking lot B of Nationals Park on September 16, 2013 in Washington, DC. A shooting rampage Monday at a US naval base in the heart of Washington claimed at least 12 lives, including the unidentified gunman, while another possible suspect was still at large, police said. The shooting sparked a massive show of force as police and federal agents surrounded the Navy Yard, cordoning off streets only blocks from the US Capitol, home of Congress. US officials gave no indication of any link to terrorism while police said the motive for the attack on the naval installation was unknown. 'At this hour, it appears that we have at least 12 fatalities,' Washington DC police chief Cathy Lanier told a press conference. AFP PHOTO / Mandel NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)

  • US-MILITARY-SHOOTING

    A woman steps out of a bus which arrived at parking lot B of Nationals Park which has been set up as a gathering point for families of the Navy Yard shootings on September 16, 2013 in Washington, DC. A shooting rampage Monday at a US naval base in the heart of Washington claimed at least 12 lives, including the unidentified gunman, while another possible suspect was still at large, police said. The shooting sparked a massive show of force as police and federal agents surrounded the Navy Yard, cordoning off streets only blocks from the US Capitol, home of Congress. US officials gave no indication of any link to terrorism while police said the motive for the attack on the naval installation was unknown. 'At this hour, it appears that we have at least 12 fatalities,' Washington DC police chief Cathy Lanier told a press conference. AFP PHOTO/Mandel NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)

  • Shooting At Washington DC Navy Yard Reportedly Leaves Several Wounded

    WASHINGTON, DC - SEPTEMBER 16: Family members of Navy Yard complex employees gather outside a parking lot that was converted to a point of reunion at Nationals Park in the wake of the Navy Yard shooting September 16, 2013 in Washington, DC. Police believe at least one gunman shot and killed 12 people and wounded others in an incident that put parts of the city on lockdown. (Photo by Win McNamee/Getty Images)

  • US-MILITARY-SHOOTING

    A US marine guards the entrance of a garage building oposite the US Navy yard on September 16, 2013 in Washington.A shooting rampage Monday at a US naval base in the heart of Washington claimed at least 12 lives, including the unidentified gunman, while another possible suspect was still at large, police said. The shooting sparked a massive show of force as police and federal agents surrounded the Navy Yard, cordoning off streets only blocks from the US Capitol, home of Congress. US officials gave no indication of any link to terrorism while police said the motive for the attack on the naval installation was unknown. 'At this hour, it appears that we have at least 12 fatalities,' Washington DC police chief Cathy Lanier told a press conference. AFP PHOTO/MLADEN ANTONOV (Photo credit should read MLADEN ANTONOV/AFP/Getty Images)

  • A small group holds a candle light vigil on Freedom Plaza to remember the victims of the shooting at the Washington Navy Yard, Monday, Sept. 16, 2013, in Washington. (AP Photo/J. Scott Applewhite)

  • US-MILITARY-SHOOTING

    Police cars are parked outside Navy Yard following a shooting at the Navy Yard in Washington, DC, September 16, 2013. A shooting rampage Monday at a US naval base in the heart of Washington claimed at least 13 lives, including the unidentified gunman, while another possible suspect was still at large, police said. The shooting sparked a massive show of force as police and federal agents surrounded the Navy Yard, cordoning off streets only blocks from the US Capitol, home of Congress. US officials gave no indication of any link to terrorism while police said the motive for the attack on the naval installation was unknown. 'At this hour, it appears that we have at least 12 fatalities,' Washington DC police chief Cathy Lanier told a press conference. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • US-MILITARY-SHOOTING

    Police work as they investigate a shooting at the Navy Yard in Washington, DC, September 16, 2013. A shooting rampage Monday at a US naval base in the heart of Washington claimed at least 13 lives, including the unidentified gunman, while another possible suspect was still at large, police said. The shooting sparked a massive show of force as police and federal agents surrounded the Navy Yard, cordoning off streets only blocks from the US Capitol, home of Congress. US officials gave no indication of any link to terrorism while police said the motive for the attack on the naval installation was unknown. 'At this hour, it appears that we have at least 12 fatalities,' Washington DC police chief Cathy Lanier told a press conference. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • Shooting At Washington DC Navy Yard Reportedly Leaves Several Wounded

    WASHINGTON, DC - SEPTEMBER 16: Family members of Navy Yard complex employees gather outside a parking lot that was converted to a point of reunion at Nationals Park in the wake of the Navy Yard shooting September 16, 2013 in Washington, DC. Police believe at least one gunman shot and killed 12 people and wounded others in an incident that put parts of the city on lockdown. (Photo by Win McNamee/Getty Images)

  • US-MILITARY-SHOOTING

    Police conduct an investigation into a shooting at the Navy Yard in Washington, DC, September 16, 2013. A shooting rampage Monday at a US naval base in the heart of Washington claimed at least 13 lives, including the unidentified gunman, while another possible suspect was still at large, police said. The shooting sparked a massive show of force as police and federal agents surrounded the Navy Yard, cordoning off streets only blocks from the US Capitol, home of Congress. US officials gave no indication of any link to terrorism while police said the motive for the attack on the naval installation was unknown. 'At this hour, it appears that we have at least 12 fatalities,' Washington DC police chief Cathy Lanier told a press conference. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • Shooting At Washington DC Navy Yard Reportedly Leaves Several Wounded

    WASHINGTON, DC - SEPTEMBER 16: A Park Police helicopter carries a sniper to the roof of a building on the Navy Yard complex where a shooting took place early this morning September 16, 2013 in Washington, DC. Early reports indicate that several people may have been shot, and police are still trying to determine the number of suspects involved in the shooting. (Photo by Win McNamee/Getty Images)

  • Shooting At Washington DC Navy Yard Reportedly Leaves Several Wounded

    WASHINGTON, DC - SEPTEMBER 16: Atlanta Braves first baseman Freddie Freeman enters Nationals Park, where a staging area for familes involved in the Navy Yard shooting were instructed to gather, and where the Braves were scheduled to play the Washington Nationals September 16, 2013 in Washington, DC. Police believe at least one gunman shot and killed 12 people and wounded others in an incident that put parts of the city on lockdown. The baseball game tonight has been canceled. (Photo by Win McNamee/Getty Images)

  • US-MILITARY-SHOOTING

    Police tactical units leave after responding to a shooting at the Navy Yard in Washington, DC, September 16, 2013. A shooting rampage at the Washington naval base claimed at least 12 lives including that of an unidentified gunman, city police chief Cathy Lanier told reporters Monday. Lanier said two more potential suspects were still at large after the shooting at the Washington Naval Yard and that the motive of the shooter or shooters was not yet known. 'We are confirming 12 fatalities. We had a few additional victims who were injured. They were not fatally injured,' she said, briefing reporters on a street by the base. Lanier gave more details on two male suspects seen near the scene of the shooting, a headquarters building within the riverside base, who police are hunting. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • US-MILITARY-SHOOTING

    Members of the military look out from a nearby building toward police units responding to a shooting at the Navy Yard in Washington, DC, September 16, 2013. A shooting rampage at the Washington naval base claimed at least 12 lives including that of an unidentified gunman, city police chief Cathy Lanier told reporters Monday. Lanier said two more potential suspects were still at large after the shooting at the Washington Naval Yard and that the motive of the shooter or shooters was not yet known. 'We are confirming 12 fatalities. We had a few additional victims who were injured. They were not fatally injured,' she said, briefing reporters on a street by the base. Lanier gave more details on two male suspects seen near the scene of the shooting, a headquarters building within the riverside base, who police are hunting. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • US-MILITARY-SHOOTING

    Police tactical units leave after responding to a shooting at the Navy Yard in Washington, DC, September 16, 2013. A shooting rampage at the Washington naval base claimed at least 12 lives including that of an unidentified gunman, city police chief Cathy Lanier told reporters Monday. Lanier said two more potential suspects were still at large after the shooting at the Washington Naval Yard and that the motive of the shooter or shooters was not yet known. 'We are confirming 12 fatalities. We had a few additional victims who were injured. They were not fatally injured,' she said, briefing reporters on a street by the base. Lanier gave more details on two male suspects seen near the scene of the shooting, a headquarters building within the riverside base, who police are hunting. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • US-MILITARY-SHOOTING

    Unidentified people are seen on September 16, 2013, outside parking lot B of Nationals Park which has been set as a gathering point for families of the Navy Yard shootings in Washington DC. One gunman has been killed and up to two more may still be at large after a shooting rampage at the US Naval base in Washington on Monday that left 'multiple victims' dead, the city's police chief said. 'We have one shooter that we believe involved in this that is deceased,' said Washington police chief Cathy Lanier. 'The big concern for us right now is that we potentially have two other shooters that we have not located at this point.' AFP PHOTO/MANDEL NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)

  • US-MILITARY-SHOOTING

    An unidentified woman is reunited at the family gathering site outside parking lot B of Nationals Park, which has been set as a gathering point for families of the Navy Yard shootings in Washington DC on September 16, 2013. The shooting rampage at a Washington naval base claimed at least 12 lives including that of an unidentified gunman, city police chief Cathy Lanier told reporters Monday. Lanier said two more potential suspects were still at large after the shooting at the Washington Naval Yard and that the motive of the shooter or shooters was not yet known. 'We are confirming 12 fatalities. We had a few additional victims who were injured. They were not fatally injured,' she said, briefing reporters on a street by the base. Lanier gave more details on two male suspects seen near the scene of the shooting, a headquarters building within the riverside base, who police are hunting. AFP PHOTO/MANDEL NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)

  • US-MILITARY-SHOOTING

    Police respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013. At least one unidentified gunman opened fire at the US Navy Yard in Washington on Monday and was at large after killing 'multiple' victims and wounding several more, officials said. Police and FBI agents descended on the area in force as helicopters swarmed overhead, amid reports a shooter was armed with an assault rifle and was holed up at the complex. 'We believe there were multiple deaths,' a US defense official, speaking on condition of anonymity, told AFP. The precise death toll remained unclear, the official said. A Washington DC police officer and another law enforcement officer had been shot while the gunman had allegedly barricaded himself in a room in a headquarters building, media reported.AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • US-MILITARY-SHOOTING

    A US Park Police helicopter patrols over the US Navy yard September 16, 2013 in Washington, DC. At least one unidentified gunman opened fire at the US Navy Yard in Washington on Monday and was at large after killing 'multiple' victims and wounding several more, officials said. Police and FBI agents descended on the area in force as helicopters swarmed overhead, amid reports a shooter was armed with an assault rifle and was holed up at the complex. 'We believe there were multiple deaths,' a US defense official, speaking on condition of anonymity, told AFP. The precise death toll remained unclear, the official said. A Washington DC police officer and another law enforcement officer had been shot while the gunman had allegedly barricaded himself in a room in a headquarters building, media reported. AFP PHOTO/Paul J. Richards (Photo credit should read PAUL J. RICHARDS/AFP/Getty Images)

  • Shooting At Washington DC Navy Yard Reportedly Leaves Several Wounded

    WASHINGTON, DC - SEPTEMBER 16: Emergency vehicles and law enforcement stage at the end of the 11th Street Bridge adjacent to the Navy Yard complex where a shooting took place early this morning September 16, 2013 in Washington, DC. Early reports indicate that several people may have been shot, and police are still trying to determine the number of suspects involved in the shooting. (Photo by Win McNamee/Getty Images)

  • Armed police prepare to enter the Washington Navy Yard as they respond to a shooting in Washington, Monday, Sept. 16, 2013. At least one gunman opened fire inside a building at the Navy yard. (AP Photo/Manuel Balce Ceneta)

  • A U.S. Park Police helicopter removes a man in a basket from the Washington Navy Yard Monday, Sept. 16, 2013. Earlier in the day, the U.S. Navy said it was searching for an active shooter at the Naval Sea Systems Command headquarters, where about 3,000 people work. The exact number of people killed and the conditions of those wounded was not immediately known. (AP Photo/Jacquelyn Martin)

  • Police work the scene on M Street S.E. in Washington, where a gunman was reported in a military building at the Washington Navy Yard Monday, Sept. 16, 2013. Shots have been fired and employees directed to a shelter. Police and federal agents from multiple law enforcement agencies responded to the scene and streets in the area were closed. (AP Photo/Jacquelyn Martin)

  • A police boat patrols near the scene of a shooting at the Washington Navy Yard on Monday, Sept. 16, 2013, in Washington. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning. (AP Photo/ Evan Vucci)

  • Cathy Lanier

    District of Columbia Police Chief Cathy Lanier briefs reporters on the shooting at the Washington Navy Yard in Washington, Monday, Sept. 16, 2013, where at least one gunman opened fire inside a building at the Washington Navy Yard. (AP Photo/Susan Walsh)

  • Police respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013. A gunman shot and wounded at least one person Monday in a headquarters building at the US Navy Yard in Washington and is still at large, the navy said.'There is one confirmed injury. Emergency personnel are on scene and a 'shelter in place' order has been issued for Navy Yard personnel,' the navy said in a statement. Local television reported that there were as many as five casualties and the Navy said that police had entered building number 197 in search of the shooter. The Navy said at least three shots were fired at 8:20 am (1320 GMT) in the headquarters building of the Naval Sea Systems Command. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • Washington Navy Yard

    A U.S. Park Police helicopter flies over a building at the Washington Navy Yard in Washington, Monday, Sept. 16, 2013. President Barack Obama is mourning what he called "yet another mass shooting" in the United States that he says took the life of American patriots. (AP Photo/Susan Walsh)

  • Police Work The Scene

    Police work the scene on M Street, SE in Washington, where a gunman was reported at the Washington Navy Yard in Washington, on Monday, Sept. 16, 2013. The U.S. Navy says one person is injured after a shooting at a Navy building in Washington. (AP Photo/Jacquelyn Martin)

  • A U.S. Park Police helicopter removes a man in a basket from the Washington Navy Yard Monday, Sept. 16, 2013. Earlier in the day, the U.S. Navy said it was searching for an active shooter at the Naval Sea Systems Command headquarters, where about 3,000 people work. The exact number of people killed and the conditions of those wounded was not immediately known. (AP Photo/Jacquelyn Martin)

  • Police Work The Scene

    Police work the scene on M Street, SE in Washington near the Washington Navy Yard on Monday, Sept. 16, 2013. The U.S. Navy says one person is injured after a shooting at a Navy building in Washington. Police and emergency crews gathered Monday morning outside the Naval Sea Systems Command Headquarters building, where the shooting was reported. (AP Photo/Jacquelyn Martin)

  • Police respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013. A gunman shot and wounded at least one person Monday in a headquarters building at the US Navy Yard in Washington and is still at large, the navy said.'There is one confirmed injury. Emergency personnel are on scene and a 'shelter in place' order has been issued for Navy Yard personnel,' the navy said in a statement. Local television reported that there were as many as five casualties and the Navy said that police had entered building number 197 in search of the shooter. The Navy said at least three shots were fired at 8:20 am (1320 GMT) in the headquarters building of the Naval Sea Systems Command. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • Police respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013. A gunman shot and wounded at least one person Monday in a headquarters building at the US Navy Yard in Washington and is still at large, the navy said.'There is one confirmed injury. Emergency personnel are on scene and a 'shelter in place' order has been issued for Navy Yard personnel,' the navy said in a statement. Local television reported that there were as many as five casualties and the Navy said that police had entered building number 197 in search of the shooter. The Navy said at least three shots were fired at 8:20 am (1320 GMT) in the headquarters building of the Naval Sea Systems Command. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • Scene At The Gate Of Navy Yard

  • Police respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013. A gunman shot and wounded at least one person Monday in a headquarters building at the US Navy Yard in Washington and is still at large, the navy said.'There is one confirmed injury. Emergency personnel are on scene and a 'shelter in place' order has been issued for Navy Yard personnel,' the navy said in a statement. Local television reported that there were as many as five casualties and the Navy said that police had entered building number 197 in search of the shooter. The Navy said at least three shots were fired at 8:20 am (1320 GMT) in the headquarters building of the Naval Sea Systems Command. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • Outside Navy Yard

  • Police Clear Block

  • Looking Up M Street

  • Members of the military guard a military garage near the Washington Navy Yard where a gunman was reported in Washington, on Monday, Sept. 16, 2013. The exact number of people killed and the conditions of those wounded was not immediately known. (AP Photo/Jacquelyn Martin)

  • A helicopter that has been airlifting people from the top of a building at the Washington Navy Yard circles the area after a gunman was reported at the Washington Navy Yard in Washington, on Monday, Sept. 16, 2013. The exact number of people killed and the conditions of those wounded was not immediately known. About 3,000 people work at the Naval Sea Systems Command headquarters. (AP Photo/Jacquelyn Martin)

  • Police bring in equipment by an anchor outside of an entrance to the Washington Navy Yard where a gunman was reported in Washington, on Monday, Sept. 16, 2013. The exact number of people killed and the conditions of those wounded was not immediately known. About 3,000 people work at the Naval Sea Systems Command headquarters. (AP Photo/Jacquelyn Martin)

  • Shooting At Washington DC Navy Yard Reportedly Leaves Several Wounded

    WASHINGTON, DC - SEPTEMBER 16: Construction workers wait at the end of the 11th Street Bridge adjacent to the Navy Yard complex where a shooting took place early this morning September 16, 2013 in Washington, DC. Early reports indicate that several people may have been shot, and police are still trying to determine the number of suspects involved in the shooting. (Photo by Win McNamee/Getty Images)

  • Shooting At Washington DC Navy Yard Reportedly Leaves Several Wounded

    WASHINGTON, DC - SEPTEMBER 16: Armed ATF agents stage on the 11th Street Bridge adjacent to the Navy Yard complex where a shooting took place early this morning September 16, 2013 in Washington, DC. Early reports indicate that several people may have been shot, and police are still trying to determine the number of suspects involved in the shooting. (Photo by Win McNamee/Getty Images)

  • Shooting At Washington DC Navy Yard Reportedly Leaves Several Wounded

    WASHINGTON, DC - SEPTEMBER 16: People shelter in place outside a building at the Navy Yard complex where a shooting took place early this morning September 16, 2013 in Washington, DC. Early reports indicate that several people may have been shot, and police are still trying to determine the number of suspects involved in the shooting. (Photo by Win McNamee/Getty Images)

  • Shooting At Washington DC Navy Yard Reportedly Leaves Several Wounded

    WASHINGTON, DC - SEPTEMBER 16: Police boats patrol the water outside a building at the Navy Yard complex where a shooting took place early this morning September 16, 2013 in Washington, DC. Early reports indicate that several people may have been shot, and police are still trying to determine the number of suspects involved in the shooting. (Photo by Win McNamee/Getty Images)

  • Shooting At Washington DC Navy Yard Reportedly Leaves Several Wounded

    WASHINGTON, DC - SEPTEMBER 16: A Park Police helicopter hovers above a building at the Navy Yard complex where a shooting took place early this morning September 16, 2013 in Washington, DC. Early reports indicate that several people may have been shot, and police are still trying to determine the number of suspects involved in the shooting. (Photo by Win McNamee/Getty Images)