Olive Mountain, 60, was listed in serious condition after she was transferred to the Hennepin County, Minn., hospital with burns from the fire. Neighbors said she lives upstairs in a house that had been converted to apartments.
A statement from the Fire Department said investigators determined that a damaged electrical cord from a television set ignited a box of clothes. Fire officials said the smoke detector in the upstairs apartment did not work because it had no battery.
Neighbor Paul Bays spotted the fire shortly before 8 p.m., when he was taking his dog out.
Fire officials said the blaze caused about $31,000 in property damage to the building and its contents, and that it appeared to have started in the second-floor apartment, along a living room wall.
Mountain was the only one home at the time of the fire, officials said.