A small but smoky fire forced thousands of office workers to flee Place Ville-Marie just before the lunch hour on Monday morning.
Officials say about 7,000 people in the building were forced to clear out.
Fire official say they believe the fire was caused by soldering work in the building's basement, resulting in heavy smoke seeping into ventilation shafts, and up the building, as far as the 32nd floor of the 47-story building.
Officials with Urgences-Santé say at least three people needed treatment — including one who was carried off on a stretcher and sent to hospital with what's believed to be a knee injury.