(CNN) -- Mexican President Felipe Calderon condemned Friday the torching of a Monterrey casino that killed at least 52 people as "the most serious attack on civil society that the country has seen in a long time." Calderon said the burning of the Monterrey Casino Royale on Thursday was perpetrated by "terrorists" motivated by greed.
Meanwhile, authorities in the northern state of Nuevo Leon, of which Monterrey is the capital, released a video showing how armed men arrived in three vehicles and were carrying what appeared to be gallons of gasoline.
They burst into the casino, and seconds later, dozens of people fled the casino, which was clouded with smoke and fire.
The attack lasted two and a half minutes, according to the video released by Secretary of the Interior Francisco Blake and Nuevo Leon Gov. Medina said 52 people died in the fiery attack, not 53 as earlier reported by authorities. Nuevo Leon Civil Protection Director Jorge Camacho Rincon confirmed that the final death toll was 52, but some officials were putting the death toll at 53 because one victim was pregnant.
At least 35 of the victims were women, and at least 10 were men, officials said.
Authorities have yet to determine the gender of the remaining victims.
Residents of Monterrey, Mexico's third largest city, reported a lot of confusion surrounding their efforts to determine whether their relatives were among those killed in the fire.
"Nobody really tells me anything," Alma Rosa Monsivais Estrada, 24, said of her search for her sister Maria Guadalupe.
The missing sister left for work at the casino Thursday morning, and Monsivais said goodbye to her, she said. It's unfair." She had searched for her sister until midnight, visiting at least five hospitals and clinics throughout ?? "I wanted to know where she is," a tearful Monsivais said.
"For me, she is everything, my sister, my friend," Monsivais said. Eventually, she decided to return to the Forensic Medical Service University Hospital, where authorities have taken most of the bodies.
Officials told relatives they will install a special window to handle requests from victims' families.
"It's a nightmare, and there is misinformation," Alfredo Jimenez said angrily.