Ontario's Special Investigations Unit has been called in after a woman was struck and killed by an unmarked police vehicle in Scarborough Wednesday night.

The woman, believed to be 18 years old, was struck on St. Clair Avenue East, just west of Warden Avenue, shortly before 8:30 p.m.

She was pronounced dead at the scene.

The driver of the vehicle remained at the scene.

The SIU investigates incidents involving police where there has been a serious injury, death or allegations of sexual assault.