Caledon OPP are currently on scene of a serious collision on Highway 9.
At approximately 1:25 a.m., officers and emergency crews responded to a two-vehicle collision on Highway 9 near Humber Station Road.
One driver was transported by air ambulance to a trauma centre for life-threatening injuries.
Highway 9 between Highway 50 and Humber Station Road remains closed while the OPP Technical Collision Investigation Unit assists with the investigation.
Anyone who may have witnessed the collision or has dashcam footage are asked to contact Caledon OPP.