A 45-year-old Montana woman being held in Gallatin County's jail - on a charge of assaulting a family member - died Sunday morning for unknown reasons.

The woman, whose name won't be released until her family is notified, was found on the floor in her jail cell at about 4 a.m. Sunday and was transported in an ambulance to Bozeman Deaconess Hospital, according to the Montana Department of Justice.

The woman's cause of death has not been determined, according to a bureau chief for the Montana Division of Criminal Investigations. She might have had an unknown medical condition. She had been moved into her own jail cell and was being monitored on a regular basis with periodic bunk checks, according to authorities. She never complained about suffering from any medical conditions or symptoms and officers say it appeared she might have died of natural causes.