The collision occurred on the corner of Snake and New Modder roads, at around 7.50am.
READ: Pedestrian killed on N12
ER24 spokesperson Kelly Burchell said a man in one of the light motor vehicles was critically injured, with the female passenger in the same car being moderately injured.
A man in the other car was also critically injured, while a child was moderately hurt.
All four patients were transported to hospital.
Also read: