Rescue workers recovered burned bodies and anxious residents crowded behind yellow police tape Friday waiting to hear if relatives were among the victims of an arson attack on a casino by presumed drug traffickers that killed at least 52 gamblers and employees.

Family members arrived at the morgue all through the night in Monterrey, a modern metropolis and one of Mexico's most important business centres that has recently become the target of increasing drug-related violence.

The armed assailants burst into the casino Thursday afternoon and then poured and ignited gasoline, burning the casino to the ground in what President Felipe Calderon described as the worst attack on innocent civilians in recent memory.

Calderon has declared three days of mourning, saying the assailants who set fire to the Casino Royale are "true terrorists who have gone beyond all limits."

The Mexican government is also offering a $2.4 million reward for information leading to catching the assailants who set the fire.

The Attorney General's Office said in a statement that Calderon instructed authorities to offer the reward to find those responsible for the "act of barbarism."

'God took care of us today.' —Norma Reyes, mother of casino worker who escaped

Nuevo Leon state Gov. Rodrigo Medina lowered the death toll to 52 early Friday in fire in northern industrial city of Monterrey after initially pegging it at 53 the night before.

Santiago Loera, 53, came looking for his brother, Miguel Angel, a cook at another casino who had gone to the Casino Royale to sign a new contract.

"We think he's here," Loera said.

Loera said authorities have asked him for a DNA sample.

So far, 45 of the victims have been identified.

The fire represented one of the deadliest attacks in Mexico since Calderon launched an offensive against drug cartels in late 2006.


Firefighters transport an injured colleague on a stretcher after an attack on a casino in Monterrey. ((Reuters))

Francisco Tamayo, 28, of Monterrey, said he and family members looked at about 40 bodies in search of his mother, Sonia de la Pena, 47, who loved to gamble at the casino and was there on average four days a week. They had yet to find her.

When Tamayo learned of the fire from television, he ran to the scene.

"She's probably here," said Tamayo, who repeatedly called her cellphone, only to hear that it was out of the area of service.

Calderon tweeted that the attack was "an abhorrent act of terror and barbarism" that requires "all of us to persevere in the fight against these unscrupulous criminal bands."

Attorney General Leon Adrian de la Garza said a drug cartel was apparently responsible for the attack, though he didn't name which one. Cartels often extort casinos and other businesses, threatening to attack them or burn them to the ground if they refuse to pay.

It was the second time in three months that the Casino Royale was targeted. Gunmen struck it and three other casinos on May 25, spraying the building with bullets, but no was reported injured in that attack.

The fire in the two-storey casino was reported just before 5 p.m. ET, a slow time of day when normally about 80 people play the tables and slots, said former security guard Alberto Martinez Alvarado, 30. Martinez, who was on his way home from work Thursday when he saw the fire, said the casino could hold hundreds, perhaps 1,000 people.

"We're lucky we weren't there," he said. "Why couldn't the people who did this do some honest work instead?"

State police officials quoted survivors as saying armed men burst into the casino, apparently to rob it, and began dousing the premises with fuel from tanks they brought with them. The officials were not authorized to be quoted by name for security reasons. De la Garza said the liquid appeared to be gasoline.

With shouts and profanities, the attackers told the customers and employees to get out. But many terrified customers and employees fled further inside the building, where they died trapped amid the flames and thick smoke that soon billowed out of the building.

Monterrey Mayor Fernando Larrazabal said many of the bodies were found inside the casino's bathrooms, where employees and customers had locked themselves to escape the gunmen.

Authorities commandeered backhoes from a nearby construction site and made a brief attempt to break into the casino's walls as smoke billowed from the main entrance, hindering firefighters.

Monterrey, Mexico

Maria Tomas Navarro, 42, stood weeping at the edge of the police tape stretched in front of the smoke-stained casino building. She was hoping for word of her brother, 25-year-old Genaro Navarro Vega, who had worked in the casino's bingo area.

Navarro said she tried calling her brother's cellphone. "But he doesn't answer. I don't know what is happening," she said. "There is nobody to ask."

Monterrey has seen bloody turf battles between the Zetas and Gulf cartels in recent months. Once Mexico's symbol of development and prosperity, the city is seeing this year's drug-related murders on a pace to double last year's and triple those of the year before.

Last month, gunmen killed 20 people at a bar in Monterrey. The attackers sprayed the bar with rounds from assault rifles, and police later found bags of drugs at the bar.

State police officials initially said witnesses reported hearing three explosions before Thursday's fire started, but later said a flammable material was used. The officials were not authorized to be quoted by name for security reasons.

The reports of explosions may have been the sound of the ignition of the liquid.

Norma Reyes, 45, was one of the people who received good news Thursday. Her son called her before she even heard about the fire to say he was all right. Jonathan Reyes, 25, who worked as an area supervisor, told his mother he was at the hospital trying to find out what happened to his co-workers.

"God took care of us today," she said.