At least 175 people have died in a fire that tore through a crowded nightclub in the Argentine capital, Buenos Aires.
Relatives have been identifying the dead
More than 619 others were injured when the fire broke out late on Thursday, city officials said.
Up to 4,000 people, many of them teenagers, were inside the club for a New Year performance by rock group Los Callejeros, reports say.
Officials are investigating the possibility that emergency exits at the nightclub were locked.
Argentine Interior Minister Anibal Fernandez said the blaze may have claimed more victims because the exits had been tied shut with wire, Reuters news agency reports.
"It appears they were condemned to walk into a trap," Mr Fernandez said.
Buenos Aires Mayor Anibal Ibarra said the emergency exit appeared to be shut "so that people wouldn't enter without paying" and firefighters had to break it open, Reuters added.
Officials do not yet know what caused the blaze, but witnesses say a celebratory flare was set off and foam in the ceiling caught fire.
"Someone from the crowd tossed a flare and there were immediately flames," said Fabian Zamudeo, who had been inside the club.
Such fireworks are widely used across the region for New Year celebrations, says the BBC's South American correspondent Elliott Gotkine.
Overnight, relatives rushed to Buenos Aires hospitals in a desperate search for their loved ones.
Medical officials shouted out the names of the injured as large crowds gathered at hospital entrances.
Grieving parents and friends of victims have also crowded the city's morgue.
"I want to go and identify all the corpses - I need to know where my granddaughter is," a crying woman told Reuters.
Rush to escape
Club-goers who had gathered at the venue for the concert say the building quickly filled with smoke and that people rushed for the emergency exits.
Many fainted from the smoke. Bystanders and concert-goers carried people out of the smouldering building.
Many of the dead are thought to have died from smoke inhalation.
"The fire spread in a minute and we were a mountain of people trying to escape," said survivor Ariel Monges, who lost a friend and a cousin in the fire.
"People were pushing and jumping over each other trying to get out," Jose Maria Godoy, told The Associated Press.
"It was like a human wave. As people fell down running for the door, others just simply ran over them or pushed them down."
Young club-goers at the nightclub helped emergency crews rush the injured to ambulances.
Bodies were reported to be lined up on the pavement as fire crews and rescue teams helped people out of the club.