Ontario Provincial Police say all lanes of Hwy. 400 have reopened south of Barrie after a serious collision resulted in a complete closure in the midst of the May long weekend travel rush.
Police said they received a call shortly after 11:30 a.m., for reports of a collision in the area of Hwy. 400 and Hwy. 89.
Investigators said they later determined that a wheel fell off of an SUV and flew into a vehicle travelling in the opposite direction, seriously injuring the driver.
Police said the wheel fell off of a white SUV travelling southbound on Hwy. 400 and flew into a vehicle travelling northbound.
A photo posted to Twitter by OPP Sgt. Kerry Schmidt showed significant damage to the northbound vehicle.
The driver of the car, a man in his 20s, was trapped and had to be extracted before he could be treated by paramedics.
Emergency crews said he was then airlifted to Sunnybrook hospital in Toronto with critical head and internal injuries.
A female passenger who was also in the car was taken to a local hospital with minor injuries.
All lanes of Hwy. 400 were closed at the crash scene as an Ornge air ambulance landed on the highway.
Southbound lanes later reopened and, shortly after 2:30 p.m., all northbound lanes also reopened.
Hwy. 400 is often one of the busiest travel routes in southern Ontario during the May long weekend.
Photos posted on social media show people standing on the highway with traffic completely stopped shortly following the crash.