A 60-year-old man suffered life-threatening injuries after his vehicle collided with a bus near the intersection of Avon Road and Westminster Avenue in Montreal West.
Police said the collision happened at 8:05 a.m. Thursday, during the morning rush hour.
Witnesses told police the car was heading west on Avon Road, while the bus was heading in the opposite direction.
Montreal police spokesperson Andrée-Anne Picard said the vehicle — for an unknown reason — changed lanes, colliding head-on with the bus, before crashing into a third vehicle.
Picard said they are looking at different hypotheses into what may have caused the driver to veer into oncoming traffic, including whether or not he suffered a medical emergency.
The driver of the first vehicle was rushed to hospital in critical condition.
The bus driver was treated for shock, and a passenger was also hurt, suffering minor injuries.
Several streets have been closed as collision experts investigate.