The Tsuu T'ina Nation Fire Department says it is working with the band's police service and the Calgary medical examiner's office to try to determine what happened.
The blaze on Thursday sent four people to hospital, including one man who was in critical condition.
Emergency response officials said all four of the injured were believed to be in their 20s.
Redwood Meadows fire Chief Rob Evans used the fire to call for sprinkler systems in homes, especially in rural areas, which crews can’t easily get to.
The Tsuu T'ina reserve abuts Calgary's southwest city limits.
A two-year-old boy and his 18-month-old sister died last month in a fire on a reserve near Loon Lake in northern Saskatchewan.