One person was critically injured when three tractor-trailers were involved in a crash on Canada’s busiest highway late Tuesday night.

The crash occurred shortly before midnight when one of the trucks failed to slow down as two others ahead of it stopped for construction in Highway 401's eastbound lanes near Westney Road in Ajax, Ontario Provincial Police said.

The oncoming truck slammed into the others, trapping its driver in the wreckage. The driver was extricated and airlifted to St. Michael’s Hospital, where the person received emergency medical treatment.

Three lanes were closed until Wednesday at 9 a.m. to allow police officers to conduct an investigation at the scene, to unload the trailers and to remove the vehicles from the road.

Police continue to investigate the crash. Charges have not been laid.

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