Windsor Fire and Rescue Services officials are investigating a building fire on Drouillard Road in Windsor.
Damage is estimated at $100,000. An investigator says the cause may be electrical.
One person was in the building at time the of the fire, but there are no reported injuries.
Fire officials say the blaze started around 2:30 a.m. Thursday between the ceiling of the commercial unit and the floor of the residential unit. There are three units on the second floor.