More than 100 residents were forced to evacuate their homes overnight due to fires in the Montreal region.

One fire in Longueuil started around 8:30 p.m. last night on the fourth floor of a building near the corner of Sainte-Hélène Street and Sainte-Foy Boulevard.

"Fire fighters rescued several people who were trapped on their balcony," Const. Martin Simard Longueuil said.

Investigators are still trying to confirm the cause of the fire. The fire department has asked police to investigate to see if it could be criminal.

Damages are estimated at $700,000, mostly due to smoke and water.

Capt. Serge Durocher of the Longueil police said 80 people were forced out of the building and 15 residents were rushed to hospital after inhaling smoke. Dozens are still waiting to return to their homes.

A second fire broke out at around 3 a.m. at an apartment building on Doctor Penfield Avenue. One woman in her 20s was taken to the hospital for treatment of smoke inhalation, and 100 residents were forced outside.

About 25 trucks and 60 firefighters were working to put out the fire as of early this morning. The building sustained up to $100,000 in damage.

The second fire was mainly isolated to the eighth floor of the 13-storey building. Montreal fire department spokesman Luc Robillard says the residents of two units won't be able to return to their home for at least three days because of damage.

Investigators are on both scenes trying to find the causes. Officers suspect the Penfield fire was caused by an electrical problem with an air conditioning unit.