Smoke was visible from all around Terrace as fire ripped through an old CN building by the railroad tracks Saturday afternoon.
Firefighers from both Terrace and Thornhill were called out to the old bunkhouse after flames and smoke were spotted from the east wing of the building.
Deputy Fire Chief Dave Jephson says investigators have chalked the blaze up to mischief.
Jephson says RCMP initially thought that there may have been someone inside when the fire broke out, but he says investigators found no trace of anyone inside.
At the time the call came in, the Terrace and Thornhill departments were conducting some joint training exercises in Thornhill.
Jephson says he was proud of the response by both fire crews.
The building will be demolished.