The body of a woman has been found in the wreckage caused by a house fire in the northwest Calgary community of Varsity.

Officials said earlier Wednesday that the mother of the family of four living in the home on Vauxhall Crescent was unaccounted for, but a teenaged son was able to get out.

The father and daughter were not in the home during the time of the fire, and have been accounted for.

"This is a real tragedy for the community, the family and the city of Calgary," said Calgary Fire Department spokesperson Carol Henke.

Officials say the body was discovered in a bedroom in the rear of the home.

Fire crews responded to the blaze around 5:30 a.m. MT after a 911 call. Henke said crews attempted to search the home for a person who was unaccounted for, but had to draw back because of safety concerns that the floor was compromised.

Henke said the fire damage is extensive.

"To the point that it affected the structural integrity so that fire crews did need to withdraw early in and fight the fire defensively," she said.

The cause of the fire is unknown at this time, but the fire alarms were working. The arson unit is investigating because there was a fatality.

The arson unit is investigating the cause of a fire in northwest Calgary that claimed the life of one person. (Bryan Labby/CBC)