BUENOS AIRES, Argentina - A fire that raced through a packed Buenos Aires nightclub during a rock concert killed at least 174 concert-goers and injured about 410, and investigators were looking into survivor accounts that the building's emergency exits were locked.

Grieving parents crowded the city's morgues to identify the dead - many of them teenagers - after the blaze swept through the club in the Argentine capital late Thursday, setting off a stampede for the emergency exits, witnesses said.

The fire unleashed thick clouds of black smoke, choking many inside and blocking out emergency lighting, survivors said. After the blaze was brought under control this morning, rescue workers turned a nearby parking lot into a temporary morgue, lining up dozens of bodies whose faces were covered by T-shirts.

"You couldn't see anything, the air was thick with smoke," said one survivor who identified himself only as Juan.

"People were pushing and jumping over each other trying to get out," said another concert-goer, Jose Maria Godoy. "It was like a human wave. As people fell down running for the door, others just simply ran over them or pushed them down."

City officials said it wasn't yet clear what caused the fire, but several survivors said they saw a flare hit foam lining on the roof of the concert hall, triggering a fire.

Flares are often lit by fans attending rock concerts in Argentina, which are frequently rowdy and punctuated by fireworks set off by people in the crowd.

"Someone from the crowd tossed a flare and there were immediately flames," said Fabian Zamudeo, a 22-year-old in the crowd to see a popular Argentine rock band, Los Callejeros.

"Parts of the roof started falling down in flames and people started running, knocking over the speakers and light stands," he added. "People were choking on smoke and I tried to push as many people out as I could."

Argentine authorities said they would investigate allegations by survivors that some people found the building's emergency doors locked as they tried to flee the blaze.

Minutes after the fire broke out, shirtless concert-goers charged out of the building, many carrying people on the shoulders or grouped to help ferry to safety.

Alfredo Stein, an official in the Buenos Aires health department, told reporters at least 174 had been killed and more than 410 people injured.

Many of the dead were believed to have suffered from smoke inhalation, said Mariano Tili, a Buenos Aires city official helping in the rescue effort.

Argentine media reported as many 1,500 people were believed to have been in the building at the time, with some saying the amount could be almost twice as much.

"This is a true disaster ... particularly with so many young people and kids inside," said Interior Minister Anibal Fernandez.