An 86-year-old woman is dead and 10 other people including three children are injured after a multi-vehicle collision on Highway 401 near Leslie.
Ontario Provincial Police said four vehicles were involved.
Toronto paramedics say a woman was transported with life-threatening injuries to a hospital, where she was pronounced dead.
Police said 10 other people suffered non-life-threatening injuries.
The cause of crash is unknown.
All westbound express lanes on Highway 401 were closed at Warden Avenue for the investigation but have since reopened.
