The northbound lanes of Highway 400 in Vaughan, Ont., have reopened following a multi-vehicle crash early Tuesday.
Ontario Provincial Police said the collision happened around 4 a.m. at Teston Road and involved at least three vehicles.
Vaughan fire officials said one male had to be extricated from one of the vehicles. He was transported to hospital with critical injuries.
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Sgt. Kerry Schmidt said a disabled vehicle was on the left shoulder when a tow truck arriving to help was struck from behind twice, once by another service vehicle and again by another car.
Police said the police reconstruction unit attended the scene for the investigation.
The northbound lanes were reopened at 10:30 a.m.