MONTREAL - A firefighter was injured and two other people were treated for smoke inhalation in a five-alarm fire in St-Henri Tuesday.

A total of 140 firefighters and 30 trucks were called to the fire at 186 Bourget St. at the corner of Ste-Emilie St. Some firefighters were seen walking on the roof trying to douse the flames.

The fire started at about 10:30 Tuesday morning and continued into the afternoon. It was declared a five-alarm fire, the highest ranking possible.

Tenant Alexandre Lasnier said he knew he had to escape quickly.

"I saw smoke coming from the bottom of the walls," he said.

The floor of the 112-year-old structure began to cave in, making it more difficult for firefighters to safely fight the blaze. One firefighter was taken to hospital after falling from a second-floor balcony at the rear of the building and and landed in the backyard.

"He has pain to his back and to his neck, but nothing life threatening," said David Sasson, spokesperson for the Montreal fire department.

Two women, one who was pregnant and another who was 74 years old, were also taken to hospital to be treated for smoke inhalation.

The fire department said many more people could have been hurt, and some may have been killed, because a propane tank was found inside the building.

"It's supposed to be outside. It's very dangerous for us... the propane can explode," said spokesperson Sylvain Cuillerier.

The two-storey wood and brick building, used for both residential and commercial purposes, housed seven people from five families. They will be put up in a hotel for three days and will be provided clothing by the Red Cross.

Manon Lucas, a university student from France, was in the shower when she heard the fire alarm. She described seeing smoke and hearing the crackling of flames on the other side of the wall before fleeing the building.

"I'm in pajamas. I'm cold, I'm hungry," she said. Without insurance, Lucas has nothing but the pajamas on her back.

The cause of the fire is not yet determine. A unit on the second was being renovated, but it has not yet been linked to the cause of the blaze.

The damages associated with the fire are estimated to cost about $150,000.