Peel Regional Police say a man was taken to hospital after he was hit by a police cruiser in Brampton on Wednesday night.
Police said the force was responding to an unrelated call when it drove by a two-vehicle collision, near Chinguacousy Road and Williams Parkway.
The officer driving the cruiser then struck a pedestrian at the scene.
The man was transported by paramedics to a trauma centre with serious injuries at around 9:40 p.m.
Police said the Special Investigations unit invoked its mandate following the incident.
The SIU is an independent agency that investigates the conduct of officers responding to calls that have resulted in death, serious injury, or alleged sexual assault.
The SIU said the pedestrian who was hit is a 39-year-old man. The agency also said Peel police were en route to another motor vehicle collision call in Brampton.