Police are investigating what led to a fiery crash on Highway 401 that left one man dead Sunday morning.

Just before 7 a.m., a BMW travelling west near Highway 427 hit a concrete median, bouncing back into the oncoming traffic. When a tractor-trailer slammed into the car, the BMW burst into flames.

"It was fully engulfed in flames with the driver still inside … and nobody was able to get him out at that time," Ontario Provincial Police Sgt. Dave Woodford told CTV Toronto.

The BMW driver was pronounced dead on the scene. The driver of the transport truck and a passenger were taken to Sunnybrook Hospital with serious injuries, but they are expected to survive.

Police are now sifting through the charred remains of the BMW for any clues.

With a report from CTV's Scott Lightfoot