One person is dead after a two-alarm fire in the southwest neighbourhood of Strathcona Park destroyed a house early Tuesday. (Erin Collins/CBC)

A Calgary mother who used a wheelchair died in an early morning fire in southwest Calgary but her husband and son managed to escape.

Fire crews were called to the 100 block of Stradbrooke Way S.W. at about 12:45 a.m. Tuesday to find the house fully engulfed in flames.

"There was smoke everywhere and sparks were flying down the street. We have a lot of cedar shingles here and we were quite concerned," said Mike Siroishka, who lives down the street.

A relative, who didn't live in the home, told fire investigators that a smoke detector alerted the husband to the fire. He tried to help his wife — who neighbours said used a wheelchair — but was forced out by smoke.

The cause of a deadly fire that destroyed a southwest Calgary house Tuesday is under investigation. (Erin Collins/CBC)

The man and his son were able to get out of the house safely but were taken to the hospital with smoke inhalation.

Crews tried desperately to reach the woman but were only able to find her body on a portion of the upper-level floor that had collapsed down to the main level, said Jeff Budai, a fire department spokesman.

"When crews arrived it was fully involved, shooting through the roof. We had a gas line off, which wasn't helping us at all," said district fire chief Russ Humphries. The leaking gas briefly threatened three other houses, sending flames and embers across the street, he added.

"I tried to go with my extinguisher to my neighbours, but after I came to the house I understood that it's impossible," said next-door neighbour Pavel Bondarev, whose house was damaged by the flames.

The fire destroyed the Strathcona Park home, valued at an estimated $750,000 for the structure and contents, while a house next door suffered about $400,000 in damage, said investigators.

A couple of nearby homes suffered minor damage to shingles from burning embers blown onto their rooftops.

Fire officials said they were focusing on the rear deck of the home to find a cause for the blaze, but it's not considered suspicious at this time.