South African police have arrested three people in connection with the deaths of 21 partygoers in an East Cape nightclub in June, including the 52-year-old owner of the venue for allegedly serving underage attendees alcoholic drinks.

The shocking mass death event took place on the night of June 26, when dozens of young people at the Enyobeni nightclub reportedly “collapsed” in what local authorities initially suspected was a stampede. Some of the victims were as young as 13, police said.

South African investigators have since ruled out the stampede theory, but toxicology reports on the dead have not yet been publicly released.

Speaking to the BBC, one 16-year-old attendee described seeing others at the nightclub suddenly “drop like flies” after gathering to celebrate the end of high-school midterm exams. She described the event as a free for all, adding that “the venue was packed. Entrance was free… and free alcohol was also being dished out. We started drinking and having fun with others.”

According to local media, some attendees reported a “suffocating smell” in the tavern as one young person after another fell to the ground or on the tables.

Another survivor, 19-year-old Sinovuyo Monyane, told AFP that “We tried moving through the crowd, shouting ‘please let us through,’ and others were shouting ‘we are dying, guys,’ and ‘we are suffocating’ and ‘there are people who can’t breathe.’”

Footage taken on that harrowing night showed busy crowds moving through Enyobeni tavern shortly before the deaths, with loud music blaring shortly before reports surfaced that something had gone terribly wrong at around 4 a.m. local time.

In the aftermath of the reports, family members and loved ones of those in attendance began to gather outside the venue, which had been cordoned off by police, with some even trying to force their way through the gates in an effort to get to the victims.

Though the exact cause of the deaths remains unclear, South African President Cyril Ramaphosa has promised to take action to stop the “scourge of underage drinking” in the country.

“We do not know yet exactly what killed our children. But we do know that the law was broken that night, and probably many nights before then,” Ramaphosa said at a memorial service for the victims last week.

Besides the bar owner, two other men working at the venue, a 33-year-old and a 34-year-old, were arrested over the incident this week.

The owner is set to appear in court on Aug. 19, according to AFP.