MONTERREY, Mexico -- Mexicans have endured plenty of horrific crimes during their country's bloody five-year war against drug gangs: bodies hanging from overpasses, beheadings, mass slayings of migrants and gunfights on crowded steets.
The torching of the casino that killed at least 52 people on Thursday, however, was a shocking new low for many.
In a nationally televised speech, an angry President Felipe Calderon declared three days of mourning on Friday and labeled the attack on the Casino Royale in Monterrey the worst against civilians in the nation's recent history.
"We are not confronting common criminals," he said. "We are facing true terrorists who have gone beyond all limits."
The attack was different than others in recent years in that the victims weren't cartel foot soldiers or migrants resisting forced recruitment by gangs. They were part of the middle class, working or gambling in an affluent part of a city that was once considered one of Mexico's safest.
"The media impact that this has is greater, because we're talking about an attack on a civilian population of a certain income," said Jorge Chabat, an expert in safety and drug trafficking at the Center for Research and Teaching in Economics. "Because who was there was from the middle class, the upper middle class of an important city in Mexico."
As the country took in the grisly details of the attack, some said a new, macabre milestone had been reached in a conflict that's claimed nearly 40,000 people since Calderon launched his drug offensive in December 2006. Calderon urged his people to unite against the cartels.
"Today, Mexico is upset and saddened and we have to transform this sadness and this grief into courage and valor to face ... these criminals," said Calderon, who did not say whether his government would alter its offensive against the cartels.
Calderon announced he is sending more federal forces to the city of 1 million people.
Hours later, he appeared in front of the burned-out casino and held a silent, minute-long vigil.
A surveillance tape showed eight or nine men arriving in four cars at the casino and setting fire to the building within minutes. The gunmen had ordered people to leave before setting the fire, but many fled further inside.
Officials said they likely died quickly, the majority from smoke inhalation.
In the streets around the casino on Friday, people said the latest violence deepened their sense of vulnerability. In recent years, the city has been ensnared in a turf battle between the Gulf cartel and its offshoot, the Zetas, and is on track for record levels of killings this year.
The casino was attacked twice before. In May, gunmen strafed it from the outside. Last month, gunmen killed 20 people at a bar.
"What happened last night was the limit," said a man nursing a Coke at a hamburger stand across from the city's morgue, where families streamed in all night to identify bodies. Like many people, he refused to give his name out of fear.
"We don't know how to protect ourselves or whom we're talking to," he said. "We don't have security right now."
The attack has resonated in Mexico because many of the victims were from the middle class, so far mostly untouched by violence, Chabat said.
Other attacks have claimed more victims – a mass grave uncovered last year had the bodies of 72 migrants – but the beheadings, dismemberings and other everyday horrors have mostly touched people in lower economic classes, Chabat said.
Thirty-five of the casino victims were women and 10 men, authorities said, an indication at the popularity of the games among women who came to play bingo or slots in the afternoons. The gender of the other seven couldn't be determined.
Civil protection and the state Attorney General's Office are investigating whether the casino had adequate safety measures and emergency exits. There were conflicting accounts from survivors that exit doors to the parking area were locked.
So far, authorities have failed to establish communication with the legal representatives and owners of the casino. They released the name of the company as Vallarta Attractions and Emotions and CYMSA Corp.
Firefighters entering the building to control the fire found 16 bodies of people who apparently tried to take refuge from the gunmen near the emergency exits and became trapped by flames and smoke, authorities said. Others were found in offices and bathrooms.
Jorge Camacho Rincon, civil protection director for the state of Nuevo Leon, where the casino is located, said gunmen had attacked casinos before but have never set fires. When people ran to hide, they reacted appropriately, he said.
"They sought places to protect themselves from firearms," he said. "They went running to closed areas."
Most were found clutching cell phones in their hands, a law-enforcement official who wasn't authorized to be quoted by name told The Associated Press.
Secretary of the Interior Francisco Blake Mora said in a press conference Friday that authorities were already looking for those responsible. Calderon offered a $2.4 million reward for information leading to the capture of the assailants, the same amount they give for the arrest of top drug lords.
Nuevo Leon state Attorney General Adrian de la Garza told Imagen Informativa radio that police have found three of the cars used by the assailants. He said the vehicles had been reported stolen.
The victims, including 10 injured, were either clients or employees of the casino.
Miguel Angel Loera of Monterrey had left his job as a chef at a nearby casino for an interview at the Casino Royale. A colleague last saw Loera a little more than an hour before the attack. His family went searching when he didn't come home.
"He never was late arriving home," said his brother, Juan Loera, 65, who waited with other brothers outside the morgue. On Friday, authorities told them they found Loera's identification on one of the bodies, but Juan Loera said the face was too burned to recognize.
Sonia de la Pena was a regular, playing bingo with her friends several afternoons a week, her son, Francisco Tamayo, said. He still had no word of her whereabouts Friday.
Rodrigo Medina, Nuevo Leon's governor, said the state would cover the funerals for 12 victims whose families could not afford them.
Across the state, residents were in shock. Several in Monterrey said they had no way to even process what happened.
A woman who worked across the street from the casino, and who identified herself only as Lucy, said she watched six armed men flee the casino and then saw smoke billow from the building.
For her, it was the worst moment so far in Mexico's war against organized crime.
"It means more fear, more terror, more lack of safety," she said. "There is no control."
"It's a revelation, proof that they are going to do what they want when they want in the hour that they want," she said.
Associated Press writers Jack Chang, Olga Rodriguez and E. Eduardo Castillo in Mexico City and Porfirio Ibarra Ramirez in Monterrey contributed to this report.