Three people are dead after an overnight apartment fire in Longueuil on Montreal's South Shore.

Police say the cause of the fire was "human actions," but are not calling it arson.

Firefighters received a call around 1 a.m. ET about visible flames coming from a building on Toulouse Street.

At first, the fire was too intense to get past the second floor, firefighters said.

The fire was under control at 6 a.m. ET, firefighters say. (Radio-Canada)

They evacuated the building and, on reaching the third floor, they found three people unconscious who were later pronounced dead in hospital.

In total, 80 firefighters were on site to fight the blaze.

Eleven people remained in hospital Saturday. Most suffered minor injuries such as burns, smoke inhalation and fractures from jumping from the balcony.

The fire was under control by noon, then demolition of the building began.

The exact cause of the fire remains unknown, as do the identities of the victims.

Red Cross on site

Volunteers from the Red Cross were on site Saturday to assist those affected by the fire.

In total, 80 firefighters worked to help control the blaze. (Radio-Canada)

"Whether people are insured or not, the Red Cross helps everyone," said Carl Boisvert, a spokesperson for the organization.

He said the team will work with the City of Longueuil's housing office to ensure the building's residents have a place to live.

"The help can be extended in some cases, but [generally] it's an emergency help for three days," Boisvert said.