From the article:
One 16-year-old partygoer described seeing others in the nightclub suddenly “drop like flies” after gathering to celebrate the end of high-school midterm exams
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.
Or injected?
Carbon monoxide?
That was my supposition. Signs are usually pretty obvious tho but maybe not in black people (rosy cheeks etc)