The fire department said nearly 125 firefighters were dispatched to the scene. There were no immediate reports of any injuries.
The blaze torched an east-end building that housed an oil-delivery company, fire officials said.
"There are reservoirs and delivery trucks inside," fire department spokeswoman Elise Breault said of the building, which is located in the middle of a residential area.
The flames, bursting out of numerous windows, also spread to nearby residential buildings. Firefighters smashed the windows of an adjacent duplex and blasted the flames with water in an effort to contain the blaze.
Some people who live in the neighbourhood were evacuated from their homes. Many onlookers stood in a nearby park and watched firefighters attempt to bring the blaze under control.
The director of a youth centre looked on nervously as the fire crept closer to his building.
"(It's) 30 metres from the flames," Denis Tremblay said of his centre, which was empty when the fire started.
"So, we'll see if our youth welcome centre will still be there in a couple of hours."
Tremblay said he was told that several explosions were heard in the area after the blaze began.
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