President Felipe Calderon said Friday that the United States bore some blame for "an act of terror" by gangsters who doused a casino with gasoline and set a blaze that killed at least 52 people.
The attack Thursday in Monterrey, an industrial city of 4 million just a two-hour drive from Texas, stunned Mexicans and seemed likely to mark a watershed in the country's intensifying war against criminal syndicates.
In a 20-minute televised address to the nation, Calderon gave an unusually blunt assessment of the causes of Mexico's surging violence before flying to Monterrey to place a wreath at the burned-out hulk of the Casino Royale.
He referred repeatedly to the attack as a terrorist act, elevating the conflict to a new level and casting it in terms of a broader struggle for control of Mexico.
He said rampant corruption within his nation's judiciary and law enforcement bore some blame.
But in unprecedented, direct criticism of the United States, he said lax U.S. gun laws and high demand for drugs stoked his nation's violence. He appealed to U.S. citizens "to reflect on the tragedy that we are living through in Mexico."
"We are neighbors, allies and friends. But you, too, are responsible. This is my message," Calderon said.
He called on the United States to "once and for all stop the criminal sale of high-powered weapons and assault rifles to criminals that operate in Mexico."
Calderon declared three days of national mourning.
The motive of Thursday's attack wasn't clear, but authorities indicated that it might have been part of an extortion campaign against one of many casinos that operate in Mexico on the margins of the law.
President Obama condemned "the barbaric and reprehensible attack" and lauded Mexico's "brave fight to disrupt transnational criminal organizations that threaten both Mexico and the United States."
Of the 52 who died in Thursday's firebombing, 35 were women.
A video taken by a closed-circuit camera that overlooks the casino's entrance showed that the attack unfolded in 2 1/2 minutes. Four vehicles can be seen pulling into the driveway of the Casino Royale at 3:48 p.m. Gunmen jump out of the cars and enter the casino, carrying three canisters apparently filled with gasoline.
Moments later, gamblers and employees are seen running from the building. Black smoke then pours from the casino as the assailants jump into the vehicles and drive off.
Witnesses who fled the casino said the gunmen shouted at gamblers to flee before setting the building ablaze, indicating that they didn't seek a high casualty count.
Initial reports said the gunmen sprayed gunfire inside the casino, but Nuevo Leon Gov. Rodrigo Medina said none of the 52 victims discovered by Friday morning had bullet wounds.
"It was an indescribable scene," said Reynaldo Ramos of Monterrey Civil Defense. Most victims died from smoke inhalation rather than direct contact with fire, he said.
He said about 300 people were in the casino at the time of the attack.
No arrests were made immediately. The Attorney General's Office offered a $2.5 million reward for information leading to the conviction of the attackers.