Mexican President Felipe Calderon charged Friday that the U.S. government, along with American drug consumers and gun dealers, was partly responsible for the deaths of 52 people killed in an arson attack at a casino in Monterrey.

Wearing a black suit and tie as he addressed a rattled nation, Calderon blamed his northern neighbor for the devastating attack, arguing that assault-style weapons and billions of dollars in drug profits empower the criminal organizations that he said were probably behind Thursday’s fire-bombing of the Casino Royale.

“The economic power and firepower of the criminal organizations operating in Mexico and Latin America come from this endless demand for drugs in the United States,” Calderon said. “We are neighbors, we are allies, we are friends, but also, you are responsible. That is my message.”

In a short statement, President Obama condemned “the barbaric and reprehensible attack” and vowed to remain a partner in the fight against violent transnational criminal organizations.

Neither Calderon nor the Obama administration provided evidence that the assailants were part of a major drug-trafficking organization. The attackers remained at large, their identities and affiliations unknown.

But critics in Mexico were raising questions about the unregulated proliferation of casinos and the failure of the Calderon government and Monterrey city hall to adequately monitor these businesses or inspect their buildings to make sure they are not firetraps.

Sports betting, nightclubs, casinos and cantinas — businesses that deal in a lot of cash — are often used by criminal gangs to launder money. They are also frequently targeted by extortionists.

A security camera captured images Thursday afternoon of a dozen assailants pulling up in four vehicles to the front doors of the Casino Royale and entering the entertainment complex, which offers bingo and betting on sports and horse racing.

As patrons ran away from the building, some of the gunmen stood by their cars and watched them go. Other assailants rushed into the casino, pointing guns. They did not appear to be wearing masks. Three of the cars were found Friday, all reported stolen.

Within two minutes and 30 seconds of the gunmen’s arrival, black smoke and red flames appeared in the security video and the gunmen were shown driving away.

Security analysts said the speed of the attack indicated that the motive was to burn the business down, not to rob the casino or its patrons.

The governor of the state of Nuevo Leon in northern Mexico, Rodrigo Medina, said at a news conference Friday that the fire was ignited by “a group of people linked to organized crime,” but he did not specify which group or whether there were links to drug-trafficking organizations.

Asked whether the casino was torched because its owners refused to pay bribes to extortionists, the governor said that was “one line of investigation.”

Authorities said the assailants entered the casino with three cans of gasoline. Early reports suggested that they threw grenades, but the governor said they did not. It was unclear whether the attackers fired their weapons.

Medina put the death toll at 52 and said most of the victims appeared to have died from smoke inhalation and burns — not from gunshots. He reported that 43 victims had been identified, including eight men and 35 women.

The industrial and business-oriented city of Monterrey was previously immune from Mexico’s crime and murder wave, but in the past year homicide rates have soared as organized crime and drug gangs attacked each other and police and preyed upon businesses in shakedown and kidnapping rackets.

The Casino Royale is the third betting establishment targeted this month in northern Mexico. On Wednesday night, gunmen attacked the Caliente Casino in Saltillo, following a similar attack Aug. 15 at the Sun City casino there. Both of the Saltillo betting parlors are owned by a former Tijuana mayor and wealthy businessman, Jorge Hank Rhon, who was charged with harboring a large cache of weapons and later released.

There was confusion about who owned the Casino Royale, with government officials giving conflicting information.

Lizbeth Garcia Coronado, a federal congresswoman, said in an interview that she and her colleagues complained before the arson attack to the Interior Minister and the attorney general, asking why the casinos operate with so little oversight.

Researcher Gabriela Martinez contributed to this report.