Revellers have described the panic and chaos when a Buenos Aires nightclub became an inferno.
Distraught relatives waited outside the nightclub for news
Police and firefighters struggled to put out the blaze and rescue thousands of people who had been attending a rock concert in the Argentine capital.
The streets outside the club were littered with stray pairs of shoes and blackened clothes.
At least 169 people died, many of them teenagers, and hundreds more were injured in the blaze.
Most of the victims were in their teens and 20s, but there were also children as young as six among the dead and injured, the Reuters news agency reported.
Witnesses say the fire started when a flare was shot at the ceiling.
"People fired the flares into the ceiling made of cloth and rubber," 15-year-old Cecilia Arce told the AFP news agency.
"The rubber started burning - but with few or no flames - making a terrible smoke that choked you, killed you if you breathed it," she said.
"Suddenly, we couldn't see anything because of the smoke and the fire spread to the stage area," another young man told a television reporter, AFP said.
"The fire spread in a minute and we were a mountain of people trying to escape," survivor Ariel Monges, 25, told Reuters news agency.
She said she had lost a friend and a cousin in the fire, and was searching for another friend at a city hospital.
Reports say officials believe some of the club's fire exits may have been locked shut.
In the confusion, some people ran away from the exits, one witness said.
"Many people were drunk and instead of running toward the five exits, they ran to the two upstairs platforms where the bathrooms are located.
Officials are still not sure how the fire started
"There, they choked to death and were trampled," Roberto Gutierrez, a waiter at a nearby cafe who ran inside the club to help the victims, told the Associated Press news agency.
Dazed and covered in soot, those who escaped uninjured stood outside the building screaming out the names of friends.
Dozens of bodies were lined up on the pavement.
"There was a girl who must have been around 10 years old," said Fernando Justiniano, a former fireman who helped in the rescue. "She was asphyxiated, poor thing, and she was burned," he told Reuters.
Worried relatives have been gathering outside the city's hospitals, where officials have been reading out the names of the injured.
"The city does not remember such a grave situation," city health secretary Alfredo Stern said, Reuters reported.