About 200 people had to seek safety overnight after fire alarms went off in an apartment building.

Most people dressed for outdoor weather before heading out into the cold, but some residents of upper floors stayed in place and were confined to their rooms for several hours.

The alarms sounded at 2:45 a.m. Wednesday in a highrise on Joliette St. adjacent to Highway 132 in Longueuil.

Firefighters rushed to the building and determined the source of the fire was a problem in an electrical room. They extinguished the flames very quickly, although smoke did make its way into nearby buildings.

Nobody was injured.

The exact cause of the fire is still being determined.