The cause of a fatal fire in the Pleasant Hill neighbourhood remains undetermined, the Saskatoon Fire Department says.

Investigators have concluded their on-scene investigation into the fire Monday afternoon at a multi-unit complex on 21st St. West and Avenue N south, the department said in a news release.

When crews arrived they found smoke and flames coming from the building and quickly extinguished the fire.

A 42-year-old woman was found dead in a basement suite, police said in a news release.

Police arson investigators, along with members of the Major Crime Section, are continuing to investigate.

An autopsy has been ordered to determine the cause of death, which is not being treated as suspicious, police say.

Damage is estimated at $100,000.