Reward offered over Mexico casino fire
Mexico's government is offering a 30m peso ($2.4m, £1.47m) reward for information leading to those behind a casino attack which killed over 50.
Several gunmen burst into the building in broad daylight, dousing it with fuel and setting it alight.
Officials suspect organised crime was behind the attack, one of the deadliest since a 2006 crackdown on drug cartels.
US President Barack Obama condemned the attack, reinforcing his commitment to helping Mexico combat criminal groups.
"The people of Mexico and their government are engaged in a brave fight to disrupt violent transnational criminal organisations that threaten both Mexico and the United States," he said in a statement released by the White House.
At the scene
The first thing you notice as you approach the Casino Royale in central Monterrey is not just the heightened security or the helicopters hovering above.
It is the smell of burnt plastic and wood that lingers after the massive fire that ravaged this building on Thursday afternoon. The front of the charred building was destroyed not by the flames, but by a crane from a nearby construction site summoned by desperate casino employees trying to reach those trapped inside.
A white pick-up truck with a silver ribbon on it is still parked near the casino entrance. It was used to lure avid gamblers into the building with the promise of a win. Now it is a reminder that Monterrey's Casino Royale was a place for people to dream of a big win. What they got was a nightmare - trapped in a burning building.
Looking stern, President Felipe Calderon was here on Friday morning to place a wreath in memory of those who died. He has called this an "act of terror". If that is the case, then the remains of the casino are the "ground zero" of Mexico's drugs war.
"The United States is and will remain a partner in this fight."
In a tweet, Mr Calderon said 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".
He also declared three days of mourning for the victims of the fire.
The attack happened mid-afternoon when about 100 staff and customers were inside the Casino Royale in the northern Mexican city of Monterrey.
Officials initially said 53 people had died but on Friday the state governor, Rodrigo Medina, lowered this to 52.
One survivor said the gunmen burst in, threatened them and then sprayed some kind of fuel which they set alight.
"It was chaos inside. You couldn't see and the smoke was choking us. Some people didn't reach the exit and fell just metres from the door," said one woman who got out.
Another person who managed to escape said there was complete panic.
"We all wanted to get out at the same time, there was a lot of pushing and we fell to the floor," another woman told Mexican media.
"I just heard explosions and ran to save my life".
Officials said some people had hidden in toilets and offices when they heard explosions instead of trying to get out and had suffocated as smoke engulfed the building.
Some reports suggested the emergency exits had been locked.
State Attorney General Leon Adrian de la Garza said a drug cartel was believed to be behind the attack.
Officials suggested the fire may have been in reprisal for failing to pay extortion money, the Excelsior newspaper reported.
Home to some of Mexico's largest companies, Monterrey and the state of Nuevo Leon have seen rising violence as the Zetas and Gulf cartels vie for control of trafficking routes to the US.
The drug gangs are also increasingly involved in kidnapping and extortion.