A fire at the former Leamington District Secondary School, located at 125 Talbot St. west, has been deemed suspicious.
Crews responded around 9 p.m. Friday and spent all of early Saturday morning battling a blaze at the property.
Leamington Fire chief Don Williamson says firefighters arrived to find smoke coming from the gym area.
"After making entry into the building the crews found the wooden stage was on fire," he said. "Crews got that extinguished, but the fire worked its way up the wall and into the roof space."
He says the roof is made up of highly flammable materials.
"We've spent most of the night trying to put the roof fire out in between all of those different surfaces, with us ending up getting an excavator to come in and take out almost half the west wall of the gymnasium so that we could get in there to have the excavator pull the roof down for us to put the roof out," Williamson said."
Williamson says the OPP will take over the investigation.
"The fire is suspicious, there was no hydro to the building," he said. "It appears somebody or someone, or something set the wooden stage on fire inside the building and that fire worked up the wall and into the attic space."
The fire was declared out as of 7:15 a.m. Saturday.
15 firefighters responded and no injuries were reported.