MERCER, Pa. — A man's handgun went off while he was holding it as he got into his truck in the parking lot of a western Pennsylvania gun store Saturday, and the shot killed his 7-year-old son, authorities said.

Joseph V. Loughrey, 44, of Sharpsville, was getting into the truck when the 9 mm handgun discharged, wounding Craig Allen Loughrey in the chest, according to state police. The boy died at the scene at Twigs Reloading Den in East Lackawannock Township, 60 miles north of Pittsburgh.

Investigators said Loughrey told them he didn't realize there was a bullet still in the chamber. "This happens all too often where people think the gun was empty," Lt. Eric Hermick told The Pittsburgh Tribune-Review.

Loughrey was trying to sell two guns at the store – one a scope rifle and the other, the handgun, state police said. The owners told Loughrey the store doesn't buy guns so Loughrey and his son returned to the truck with them. Loughrey put the boy in the passenger seat and loaded the rifle into the truck, state police said. He was attempting to get inside and reached to put the handgun in the center storage console when it fired, they said.

Loughrey was questioned by state police, who said he was cooperative and distraught. The shooting is being investigated as an accident, although Loughrey could face charges, including manslaughter and negligence, Hermick told the Pittsburgh Post-Gazette.

"I know that little kid was everything to him," Mark McLaughlin of Fredonia, a friend and co-worker of Loughrey's at Superior Well Services in Fredonia, told the Tribune-Review.

Messages left for the coroner's office and at a listing in Loughrey's name were not immediately returned.

Also on HuffPost:

Loading Slideshow...
  • Swat team members secure the scene near Sparks Middle School in Sparks, Nev., after a shooting there on Monday, Oct. 21, 2013. Authorities are reporting that two people were killed and two wounded at the Nevada middle school. (AP Photo/Kevin Clifford)

  • Sandy Hook Elementary

    Molly Delaney, left, holds her 11-year-old daughter, Milly Delaney, during a service in honor of the victims who died a day earlier when a gunman opened fire at Sandy Hook Elementary School in Newtown, Conn., as people gathered at St. John's Episcopal Church , Saturday, Dec. 15, 2012, in the Sandy Hook village of Newtown, Conn. The massacre of 26 children and adults at Sandy Hook Elementary school elicited horror and soul-searching around the world even as it raised more basic questions about why the gunman, 20-year-old Adam Lanza, would have been driven to such a crime and how he chose his victims.

  • Police secure the scene near Sparks Middle School after a shooting in Sparks, Nev., on Monday, Oct. 21, 2013. Authorities are reporting that two people were killed and two wounded at the Nevada middle school. (AP Photo/Kevin Clifford)

  • Clackamas Town Center

    A security guard looks over the food court at the Clackamas Town Center mall as it opens, on Friday, Dec 14, 2012 in Portland, Ore. The mall is reopening, three days after a gunman killed two people and wounded a third amid a holiday shopping crowd estimated at 10,000. The shooter, Jacob Tyler Roberts, killed himself after the attack Tuesday afternoon.

  • St. Vincent's Hospital Shooting

    Birmingham police arrive at the scene of a shooting at St. Vincent's Hospital on Saturday, Dec. 15, 2012 in Birmingham, Ala. Authorities in Alabama say a man opened fire the hospital, wounding an officer and two employees before he was fatally shot by police. Birmingham Police Sgt. Johnny Williams says the officer and employees suffered injuries that are not considered life-threatening.

  • Sikh Temple Shooting

    Mourners attend the funeral and memorial service for the six victims of the Sikh temple of Wisconsin mass shooting in Oak Creek, Wis., Friday, Aug 10, 2012. The public service was held in the Oak Creek High School. Three other people were wounded in the shooting last Sunday at the temple. Wade Michael Page, 40, killed five men and one woman, and injured two other men. Authorities say Page then ambushed the first police officer who responded, shooting him nine times and leaving him in critical condition. A second officer then shot Page in the stomach, and Page took his own life with a shot to the head. (AP Photo/Jeffrey Phelps)

  • July 2012: Aurora, Colorado

    A policeman stands outside a Century 16 movie theater in Aurora, Colo., where a heavily armed man opened fire, killing at least 12 people and injuring 50 others.

  • May 2012: Seattle, Wash.

    Friends, family and employees react after a shooting at Cafe Racer in Seattle on May 30, 2012. A lone gunman killed four people Wednesday -- three were shot to death at a cafe, and a fourth in a carjacking. The gunman later killed himself.

  • April 2012: Oakland, California

    Alameda County Community Food Bank workers move a memorial from a parking spot next to Oikos University in Oakland, Calif., Monday, April 23, 2012. Some students and staff members have arrived to resume class at Oikus University, the small California Christian college where seven people were shot to death earlier in April.

  • November 2009: Fort Hood, Texas

    Panou Xiong, center, is comforted by family and friends following a Remembrance Ceremony commemorating the one-year anniversary of the worst mass shooting on a U.S. military base, where 13 people were killed and dozens wounded,, Nov. 5, 2010 in Fort Hood, Texas. Xiong's son, Pfc. Kham Xiong, was killed in the shooting. <em><strong>CORRECTION:</strong> This slide originally said that the Fort Hood shooting took place in November 2010. The shooting took place in November 2009.</em>

  • March 2009: Kinston, Alabama

    The charred Kinston, Ala. living room where suspected gunman Michael McLendon allegedly killed his mother Lisa McLendon, is photographed Wednesday, March 11, 2009. Authorities were working Wednesday to learn why a gunman set off on a rampage, killing 10 people across two rural Alabama counties.

  • August 2007: Blacksburg, Va.

    An unidentified family member of slain Virginia Tech student Daniel Alejandro Prez Cueva, pauses at his memorial stone after the dedication of the memorial for the victims of the Virginia Tech shooting in Blacksburg, Va., Sunday, Aug. 19, 2007. More than 10,000 people gathered on the main campus lawn as Virginia Tech dedicated 32 memorial stones for those killed by a student in a mass shooting on campus last April.

  • April 1999: Littleton, Colo.

    This aerial shows the news media compound near Columbine High School in Littleton, Colo., April 21, 1999. Media from around the world poured into the area after 15 people were killed during a shooting spree inside the school.