The OPP say six people have been taken to hospital following a multi-vehicle head-on collision in King Township.
The crash took place on Highway 9, east of Caledon King Townline around 6:45 p.m. Saturday evening.
Sgt. Kerry Schmidt of the OPP says three vehicles in total were involved in the crash.
One of the vehicles is believed to have drifted into the oncoming lane and hit another vehicle almost head on.
Police believe the third vehicle got involved in the crash after hitting debris on the road.
Medical air transport system Ornge said earlier that two of their air ambulances transported two people with critical injuries to Toronto-area trauma centres.
Schmidt has since added that the two people airlifted, a driver and a passenger, were occupants of the same vehicle.
The four others injured, including two who were passengers in the same vehicle with those airlifted to trauma centres, were taken to local hospitals.
No one in the third vehicle was injured.