Six people, including a child, were killed on Saturday afternoon after a truck collided head-on with a Volkswagen Polo on the R38 near Barberton in Mpumalanga.
According to the Road Traffic Management Corporation (RTMC), the accident happened after the truck was trying to overtake another vehicle.
"It is alleged that the truck was overtaking dangerously around a bend in the path of the approaching Polo sedan, and the vehicles collided," RTMC spokesperson Simon Zwane said.
An SUV then crashed into the truck and Polo.
Zwane added five people, including a child travelling in the Polo, were killed, while the truck driver also died. One other passenger in the truck was seriously injured.
"The exact cause will be subject to the ongoing investigation," he said.