From the Wikipedia post.

INCIDENT:

During a celebration of hlanjwa iphepha (pens down), a tradition in South Africa that celebrates the end of school exams, a stampede occurred at the tavern.[7] Videos of the venue prior to the disaster show that it was packed with young people, with many appearing to be underage.[8] A patron who was at the tavern told Al Jazeera that when the venue became overcrowded, security instructed people to leave, to no avail. The patron went on to state that a security guard closed the doors and sprayed a chemical into the crowd. The patron said they were unable to breathe and that "we suffocated for a long time and [were] pushing each other but there was no use because some people were dying". The substance reportedly "smelled like gas".[9]

Promise Matinise, the entertainment manager of the tavern, said they had a lack of manpower to deal with overcrowding and that some patrons tried to force their way in.[10] Matinise witnessed people falling while bouncers failed to control the large crowd and stated he contacted the owner upon discovering that the people were dead.[11]

At 4 a.m., a call was placed by a witness reporting that there were multiple deaths at the tavern.[7] Seventeen victims were found on the floor and on chairs and tables, but with no obvious signs of injury.[12][3] Two victims died at a local clinic, and two more victims died during or after being evacuated to a hospital.[12]