It happened just after 1 a.m., at the partially built École Fraser River Middle School at 8th Street and Queens Avenue.
Fire crews found a small fire in a pile of wood and sawdust close to the building.
They were able to quickly extinguish it and determine the cause, but given the extremely dry conditions throughout most of British Columbia, the fire could have quickly spread.
Officials said the fire was reported by a security guard, who was the only person at the secured construction site.
The security guard told firefighters he doesn't smoke.