The son of a 76-year-old woman, who was critically injured in a fire that tore through her south-Ottawa home, says the oxygen tank that helped his mother breathe ended any chance he had to save her.

"I got to the second step. The explosion happened and it threw me out," said Zouheir Abdul Hussein.

His mother, Sabbah Abdul Hussein, was visiting her son's home across the street on Monday when she left to get something from her own home on Marlin Private, near Hunt Club Road and Bank Street.

Soon, her son saw smoke coming from his mother's house, and ran across the street.

The fire spread quickly from the area near the living room to the second floor. Within five minutes, there was an explosion.

"The neighbours held me and wouldn't let me go back in. I didn't hear her voice after that. The firefighters, they came a few seconds after the explosion," said Zouheir.

Second-degree burns

Firefighters managed to rescue Sabbah from the kitchen. She was not wearing her oxygen tank at the time, but suffered second-degree burns to her chest and airway. She is now in an induced coma in hospital.

Her sons believe the explosion likely caused their mother's burns.

"Right now, they're saying her heart rate is not normal, and she's not breathing on her own. Just through the machine," said Ali Abdul Hussein.

He visited his mother about an hour before the fire on Monday, and remembered thinking he smelled something burning.

"One of the things the fire marshal was indicating – it could be an electrical problem because something was done on the furnace the day before," Ali told CTV Ottawa.

Proud mother, grandmother

Sabbah is described as a woman who has a zest for life. She has 16 children, and more than 45 grandchildren. Although she lived a tough life, raising a family in war-torn Lebanon, she moved to Canada about 17 years ago.

"She's very strong. She's always funny. We're sitting laughing; she always jokes and has fun," said Zouheir.

Fire officials are yet to determine the cause of the fire. However, firefighters say oxygen tanks can be extremely flammable, and precautions must be taken whenever an oxygen tank is stored in a home or building.

"Have clear signage and make sure that people around know that people are using oxygen," said Pierre Savary, the information officer for Ottawa Fire Services.

With a report from CTV Ottawa's John Hua