Three people died and another three were seriously injured following a major accident involving a quantum minibus and a bus on R61 between Aberdeen and Beaufort West on Saturday morning.
Western Cape Traffic Chief Kenny Africa said the accident happened about 60km from Aberdeen shortly after 04:00.
Africa said the minibus, which was travelling from the Western Cape to Eastern Cape, is believed to have had a tyre burst resulting in the driver losing control and the vehicle overturning.
He said some of the passengers had been ejected from the vehicle and had landed on the road.
"It is further alleged that a bus traveling from the Eastern Cape to the Western Cape, drove over the injured that were lying in the road," he said.
Africa said a man and woman from the minibus died at the scene, while three more passengers were seriously injured and were taken to Midland hospital in Graaff Reinet.
He said one of the patients taken to hospital had later succumbed to their injuries.
The rest of the passengers were slightly injured and were treated at the scene. Both drivers are unharmed.
Africa said the cause of death of the two passengers still needed to be determined - as it was not clear if it was as a result of the minibus that overturned, or because of the bus that drove over them.
The R61 was still closed to traffic early on Saturday morning, and officials were on scene.
Africa said the Aberdeen police had opened a case of culpable homicide.