VIDEO/PHOTOS: The cause of the deadly fire in Millwood that killed two children and two dogs was due to an improper disposal of cigarettes, according to the Spokane Valley Fire Department. The fire department says the cigarette was disposed of in combustible materials outside the house. Fire crews returned to the home Tuesday morning to continue its investigation of the fire. The Spokane Valley Fire Department says the investigation has been closed. The fire started in the Millwood home just east of Millwood Park at around 2:45 a.m. Monday morning, around seven blocks away from the Spokane Valley Fire station. Two children were located inside the home. The Spokane Valley Fire Department says firefighters could see dark smoke when arriving, upgrading the fire to a working fire.