A 46-year-old woman suffered life-threatening injuries after being pinned under a car in Newmarket on Tuesday evening.
Police say the accident happened in the intersection of Davis Drive and Longford Drive just after the dinner hour.
The pedestrian had to be airlifted to a Toronto trauma centre.
The 87-year-old woman who was driving the vehicle remained at the scene.
Investigators are working to determine what happened. It is unclear if the weather was a factor.
Anyone with information or dashcam video is asked to contact police.
