MEXICO CITY — His voice cracking with emotion, President Felipe Calderon said Friday that the United States bears some blame for "an act of terror" by gangsters who doused a casino with gasoline and set a fire that killed at least 52 people.
The attack Thursday in Monterrey, an industrial city of 4 million barely 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, at least linguistically, 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 also must bear some blame.
But in unprecedented, direct criticism of the United States, Calderon said lax U.S. gun laws and high demand for drugs have 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," 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.
In a statement, President Barack 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."
The motive for Thursday's attack wasn't clear, but authorities indicated that the attack might have been part of an extortion campaign against one of many casinos that operate in Mexico. The Casino Royale was the third betting establishment to be targeted this month in northern Mexico.
Calderon's blast at the United States underscored the feeling here that there's little appreciation north of the border for the role Americans have played in strengthening the cartels that are responsible for the grisly violence that has claimed as many as 40,000 lives in the past five years.
With weapons bought in the United States, the gangs, which have roots in drug smuggling but have branched out into a variety of criminal enterprises, are better armed than the police. While Calderon's government has captured dozens of mid- and upper-level gangsters, beheadings, public executions and kidnappings are epidemic.
Of the 52 who died Thursday, 35 were women — mostly in their 40s, 50s and 60s — who were passing time in the casino on a weekday afternoon, officials said. Ten people were injured.
The Attorney General's Office offered a $2.5 million reward for information leading to the conviction of the attackers.