BUENOS AIRES, Argentina (AP) – Anguished families struggled Saturday to identify the bodies of relatives killed in a Buenos Aires nightclub fire that left at least 186 people dead, many after being trapped inside by locked emergency exits.

The club’s owner, Omar Chaban, was being held by authorities pending an investigation into Thursday’s inferno. Judicial officials said they were looking into claims the building was overcrowded at the time of the blaze, which also injured more than 700 people.

Authorities raised the death toll from 175 after 11 more deaths were reported. Some 100 people remain in critical care in city hospitals, and police warned the death toll could rise.

Several hundred people later Saturday marched near the Cromagnon Republic nightclub, calling on city officials to toughen safety codes for concert halls and rock clubs.

“We have to ensure this never happens again,” said Jorge Viegas Mendes, whose 18-year-old son, Cristian, died in the blaze.

Police were also looking for three business partners of Chaban’s who have not contacted investigators since the fire.

Investigators said they believed one of Argentina’s worst disasters began when somebody set off a flare during the concert, igniting the foam ceiling of the Cromagnon Republic club while it was crowded with about 4,000 mostly teenage fans of the Argentine rock band Los Callejeros.

The building had a capacity for some 1,500 people, city officials said.

The fire triggered a stampede for the exits as the concert hall filled with choking black smoke. Survivors told of people struggling to force open emergency exits, which authorities said were either tied shut or padlocked to prevent people from entering without paying. Many of the victims died from smoke inhalation, city officials said.

Dozens of families gathered at the city’s morgues to identify the bodies of relatives while volunteer psychologists circulated among the crowd hoping to console relatives. Some were still searching for lost loved ones, and frantically scanned lists of the injured, missing, and dead posted near the morgue.

One woman, Paula Espindolam, said she had not been able to find her 30-year-old cousin two days after the blaze.

“She’s on the list of the disappeared, but we don’t know if she’s dead or injured. I’ve searched the hospitals, everywhere, but haven’t been able to find her,” she said.

Officials said more than a dozen people believed to have been inside the nightclub remain unaccounted for and Argentine media published lists with descriptions of the missing – many of them teenagers – with details of clothing, tattoos, and hair and eye color in an effort to help locate them.

On a sweltering day in the Southern Hemisphere summertime, neighbors and concerned citizens carried bottles of water, plastic chairs, and food to family members and relatives awaiting news at city morgues and hospitals.

“This has been a tremendous tragedy and I wanted to find some small way that I could help,” said Estefania Vonkorfs, 16, as she handed out bottles of water. Vonkorfs said she had been moved in part because she had originally planned to attend the concert, but wasn’t able to buy a ticket.

At least 72 victims have been identified, officials said, but the process was being slowed since many of the dead were teenagers who were not carrying identification.

At the site of the club in a working-class Buenos Aires neighborhood, Argentines left candles, flowers and a small group held hands and bowed their heads in prayer to remember the victims.

Investigators said they had identified three people believed to have launched the flare that ignited the fire, but were trying to determine if they could be among the dead.

Police said they were also investigating survivor accounts that a bathroom inside the nightclub had been used as a makeshift nursery, where parents left their kids during the show. Dozens of young children were among the victims.

The fire and its aftermath hung over New Year’s festivities in the Argentine capital, where Buenos Aires city officials declared a three-day mourning period and ordered all night clubs closed during the weekend.