The arson squad is investigating several fires that took place Wednesday night and Thursday morning.
The earlier fire began around 10:30 p.m. in a four-storey building on Jean Talon St. between Louis-Hemon St. and Des Ecores St.
A depanneur and a nail salon were located on the ground floor, with offices above and apartments on the top floor.
Most of the damage occurred to the ground floor stores.
A second related fire took place at a greengrocer on Fleury St.
Around 1 a.m. Thursday firefighters rushed to Fleury near Hamel Ave. after getting multiple 9-1-1 calls.
The fire was extinguished in about 90 minutes and firefighters then notified police.
Both fires are being investigated because they appear to have been deliberately started.