Huntsville OPP are investigating a fatal head-on collision on Highway 60.
A small vehicle was travelling westbound Sunday afternoon around 4 when investigators say the vehicle crossed the centre line and struck an empty tour bus at the west entrance to Algonquin Park.
The vehicle flipped over striking another vehicle in the process.
Two people were pronounced dead at the scene, one was airlifted to a Toronto hospital with serious injuries, two more were treated for non-life threatening injuries in hospital.
Members of Algonquin Highlands Fire, Lake of Bays Fire, Muskoka EMS, and Algonquin Park staff also attended the scene.
