Ontario Provincial Police say speed was possibly a factor in a serious crash on a Highway 401 ramp in Toronto early Sunday.
Emergency crews were called to the Keele Street westbound ramp to Highway 401 around 3:30 a.m.
According to a tweet posted to the OPP Twitter account, a vehicle rolled over and the driver was taken to hospital with life-threatening injuries.
Police said there were no other people inside the car.
The daily email you need for
Toronto's top news stories.
Roads were closed in the area for the investigation.
Witnesses are being asked to contact police at 416-235-4981.