All southbound lanes of Highway 400 have now reopened at Finch Avenue following a fatal multi-vehicle collision which occurred on the busy highway early this morning.

The three-vehicle collision happened near the Highway 401 split around 5:10 a.m.

Ontario Provincial Police said a BMW was travelling at a high rate of speed when it struck the rear of a box truck. One other passenger vehicle was involved, but police did not say how.

One adult was pronounced dead at the scene, Toronto Paramedic Services said. No other injuries were reported.

OPP said the person who died was in the BMW. Three other people who were in the car fled on foot after the crash, police said.

"Anyone with information pertaining to this investigation is encouraged to reach out to #TorontOPP," OPP said in a post on X.

All southbound lanes of Highway 400 were closed between Finch Avenue and Highway 401 for most of the morning as OPP investigated the deadly collision. They reopened around 11:20 a.m.