Torrance Fire Department is investigating a fatal apartment fire on the north side of the city.

Crews reported to a second-alarm fire around 3:15 p.m. Monday in the 16900 block of Yukon Avenue. One unit was in flames at a garden-style apartment building. Fire officials say once they arrived they saw heavy smoke coming from the rear bedroom window.

The smoke made it difficult for them to make entry to the residence. Once inside, they searched the apartment and found a deceased female approximately 55 to 60 years old in a back room.

Crews were able to knock the fire down in under 10 minutes. Torrance Police detectives are working on the case along with Torrance Fire Prevention. Authorities are investigating on how the fire may have started.