A wheel from a car on one side of Highway 400 hit another car - causing serious injury.
OPP Sgt Kerry Schmidt says just after 8:15 this morning, the wheel came off a car on the northbound side at Highway 89, and hit another car on the southbound side.
The 29 year old victim, a woman from Barrie, was airlifted to hospital with very serious injuries.
Her car was severely damaged on the roof and windshield from the wheel.
Ornge Air Ambulance says on Twitter that this is their third response in the last month, involving tires separating from vehicles.
Schmidt says a all lanes are open in each direction now between 89 and Innisfil Beach Road.