MOORHEAD, Minn. (AP) — A Minnesota state fire marshal's investigator has determined a Moorhead apartment fire that killed a woman was caused by smoking materials in the bedroom.

Moorhead police on Thursday identified the victim as 58-year-old Billi Jo Larson.

Assistant Fire Chief Jeff Wallin tells KFGO-AM firefighters found smoke and soot coming from one of the apartments on the lower level of the building Wednesday. The victim was found in that apartment and was rushed to Sanford Medical Center in Fargo, North Dakota, where she was pronounced dead.

Police say the fire was ruled accidental. The official cause of death is still pending the final autopsy report.

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