Damage is pegged at around $150,000 following a vacant duplex fire on Cataraqui St. and Pierre Ave. in Windsor.
Fire crews responded to the blaze just before 2am on Monday.
Fire officials say firefighters faced heavy flames on the first floor when they first arrived. Those flames spread quickly to the second floor, and at one point were shooting through the roof of the duplex.
No one was injured in the fire.
An investigator attended the scene in the morning but the cause remains undetermined due to the extensive damage.