The couple's 13-year-old son suffered critical injuries, said Netcare 911 spokesperson Chris Botha.
"Paramedics arrived at the scene and found the roadway severely obstructed with accident debris and the twisted frames of the vehicles. Some of the occupants were still trapped in the twisted metal of their cars," Botha said.
Three occupants of the other vehicle all escaped with minor injuries.
"[They] were treated on scene and then transported to various hospitals for the care that they required," said Botha.
The exact cause of the accident would be investigated by the police.