The M1 north highway was blocked off at the Empire Road due to an accident, says Johannesburg Metro police.
JMPD spokesman Wayne Minnaar said an ambulance overturned at the Jan Smuts off ramp and while officers were attending to the scene a taxi and a van collided into a stationary patrol vehicle.
He said the accident was causing traffic to back up along the highway on Monday morning.
"As it is raining this morning, motorists are reminded to reduce travelling speed and keep a safe following distance as roads are wet and slippery."
