Fire has destroyed part of the former Centralia College at Huron Park.
The blaze was spotted just before midnight in the former Bruce Hall building. It's been empty for years but was undergoing renovations by a new owner.
Firefighters and equipment from Huron Park, Exeter, Dashwood, Hensall and Lucan were on the scene all night.
South Huron Fire Chief Jeremy Becker is quoted as saying the windows in the building were all open, which fed the fire and it spread quickly.
The three-storey building was gutted by the fire. The cause is unknown, and the fire chief was not sure if the building will be safe for investigators to enter.