A motorist driving by the shop on Marcel-Laurin Boulevard called in the fire around 3:20 a.m. on Wednesday.
Southbound Marcel-Laurin Boulevard is closed between Henri-Bourassa Boulevard and Poirier Street as a result.
No one was inside the two-storey building when the fire started.
Ian Ritchie, operations chief for the Montreal fire department, said the potentially criminal case has been transferred to the Montreal police.
"There are certain elements on the scene that lead us to believe it could be a criminal fire," Ritchie said.