Netcare 911 paramedics and other services responded to an accident on the R59 in Meyersdal, Alberton this morning.
Upon their arrival on scene they found a motor vehicle and heavy goods vehicle had collided and the motor vehicle then overturned.
Three people were found in a serious condition and transported to hospital for further medical care.
Exact detail to the cause of the accident and preceding events will remain the subject of a police investigation.