All westbound lanes of Highway 401 are being closed in Whitby following a multi-vehicle crash in Ajax.
It happened at Salem Road at around 10:30 p.m.
The circumstances surrounding the collision, which involved at least one transport truck, were not immediately known.
Vehicles are currently pinned under the truck, OPP Sgt. Kerry Schmidt told CP24.
As many as 18 vehicles in addition to the truck are involved in the crash, Ornge said.
The number of people injured and the severity of their injuries was not immediately known.
Police and emergency crews are responding to the scene.
The westbound lanes of the highway have been closed at Brock Street. There was no immediate indication how long the closure might last.
