Police arrested two people Tuesday after they found what is believed to be a marijuana grow-op at a residential building in Cote St. Luc.

Firefighters responded to a call for a small fire around 11:50 a.m. at Mackle Manor, at 6625 Mackle Rd. The fire had broken out in an apartment on the first floor of a 10-storey building.

When firefighters entered the apartment where the fire started, they discovered a marijuana grow-op, police say.

A man in his 30s and a woman in her 60s were arrested. Police handcuffed the two suspects and walked them to police cars as residents looked on.

“The cause is still under investigation, we don’t have any more information for now,” explained Bruno Rousseau, chief of operations for the Montreal fire department.

All 81 units were safely evacuated.

“The alarm went off and I looked outside my bedroom window and I saw smoke,” said Arlene Sculnick, who lives in the building.

There was no damage to the rest of the building, only where the fire started, and no one was hurt in the blaze, though it caused quite the commotion when it broke out.

“It's literally what you would see in the movies when you see a house blow up or a fire inside a house. With the smoke and the fire billowing out the windows, it was quite a sight, I'll tell you that,” said Marshal Chazan-Levigne who parents live in the building.

About 70 firefighters were called to the scene. Rousseau said they were concerned because it is a big building and because of the heat.

The Montreal police's arson squad has taken over the investigation.