Buenos Aires, Argentina ? Emergency exits at a nightclub packed with teenagers were padlocked or wired shut when a flare ignited the foam ceiling, sparking a blaze that killed 175 people and injured more than 700 in one of Argentina’s worst disasters, survivors and officials said Friday.

Some 4,000 fans at a Thursday night concert by the band Los Callejeros fought to reach the exits as burning debris fell on them. But they found at least four escape routes locked in an apparent effort to prevent people from entering the club without paying, Buenos Aires Mayor Anibal Ibarra said.

“Had they been open, we surely would have avoided a lot of deaths,” Ibarra said, calling the locked doors at the Republica de la Cromagnon disco an “irresponsible act.” The club’s name means Cromagnon Republic.

Police want to question the club’s owner, who vanished during the inferno. The concert crowd was nearly three times the venue’s capacity of 1,500 people, Argentine media reported.

Investigators think the fire was caused by a flare lit during the concert by a fan. People attending rock concerts in Argentina frequently set off flares and fireworks, and survivors said band members appealed to fans at one point during the show to refrain from lighting fireworks.

At least 714 people were injured, officials said. At least 102 were in critical condition, said Julio Salinas, an official with the Buenos Aires emergency services department.

The fire tore through the concert hall in the working-class neighborhood of Once, filling the club with thick, black smoke.

“Someone from the crowd tossed a flare and there were immediately flames,” said 22-year-old Fabian Zamudeo. “Parts of the roof started falling down in flames and people started running, knocking over the speakers and light stands. People were choking on smoke and I tried to push as many people out as I could.”