Crews from three fire departments were called to a house fire west of Owen Sound early Wednesday morning.
Grey County OPP say the first reports of the fire came in around 3:20 a.m.
Dispatched to Sideroad 115, north of Jackson in the Township in Georgian Bluffs, were firefighters from the Chatsworth, Wiarton and Inter-Township fire departments, as well as police and paramedics.
Arriving at the scene, they found a two-storey farmhouse fully engulfed in flames.
Four people who had been in the structure were taken to hospital.
Three of the four have since been released, while the fourth was airlifted to a Toronto hospital with injuries described as serious.
Information on the cause of the fire and a damage estimate was not immediately available.
