A fatal crash is expected to close down the westbound lanes of Highway 401 in Whitby, Ont., for several hours.
The Ontario Provincial Police say the collision involved four vehicles, including a motor coach and a transport truck.
One person has died and police say two others have serious injuries.
The collision occurred in the westbound lanes of the highway near Thickson Road.
The eastbound lanes of the highway have been temporarily closed to allow an air ambulance to land. Once patients are transported, at least one lane on that side of the highway will reopen.