Investigators have ruled that a Myersville house fire that took the lives of two young sisters was caused accidentally Investigators from the Frederick County Fire Investigation Task Force have determined that the fire started in the area of a baseboard heater in the first floor living room, according to a news release from the Frederick County Sheriff's Office The heater was behind a couch, where it came into contact with drapery in the room Once the drapes ignited, the fire quickly spread to the furniture in the room