Sault Fire Services responded to a fire at Boniferro Mill Works early Tuesday.
Damage to a part of the hardwood sawmill at 45 Third Line West was "extensive," said Sault Fire Services Platoon Chief Stan Martynuck, speaking to SooToday.
Two firefighters suffered minor injuries not requiring medical treatment.
Fire crews arrived at the mill shortly after 2 a.m. and were on scene until 10:30 a.m.
The fire is not considered suspicious in nature.
The electrical fire began in the hydraulic debarker room and spread to some other rooms in the mill, Martynuck said.
A total of six Fire Services vehicles, including four pumper trucks and a rescue truck, went to the scene.