The left lane of Highway 403 is blocked at Aberdeen Avenue for an injury investigation.
OPP briefly closed the westbound highway following a reported collision.
OPP Sgt. Kerry Schmidt said a transport truck ran into the guardrail along the westbound 403 shortly before 4 p.m. and the male driver was found without vital signs.
Schmidt said it was unclear at 4 p.m. whether the man suffered a medical problem or was injured in a collision.
Emergency medical personnel, fire and police officials are on the scene.
More to come.