OPP in Orillia say a youth riding a bicycle was struck by a vehicle around 3:30 Sunday afternoon.
Police did not identify the gender or age of the person, but say the youth was transported to a local hospital and then airlifted to a Toronto hospital with life-altering injuries.
Police confirmed to Barrie 360 that the cyclist was wearing a helmet.
The collision happened on West Ridge Boulevard at Vanessa Street as the rider was crossing the road.
The investigation is ongoing.