Ottawa Fire officials say there was about one-million-dollars' damage in a three-alarm blaze at St. Francis of Assisi School on Watters Road at Charlemange Drive in Orleans early Tuesday morning.
Several 911 calls came in shortly after 2 a.m. from nearby residents.
Firefighters say the flames began in roofing material on the roof.
They thought they had the fire contained, but a third alarm was turned in when the flames moved into theĀ building's ductwork.
No injuries were reported.
The Ottawa Police Arson Unit is involved in the investigation, along with the Ontario Fire Marshall.