A discarded cigarette caused the fire that ripped through a South Hill apartment complex last week and left 29 homeless, the Spokane Fire Department said today. The three-alarm blaze at the Regal Ridge apartments, 5111 S. Regal St., May 13 left a hole in the roof of the 10-unit building, but a fire wall in the middle of the building saved five units from serious damage. The 17 adults and 12 children who live in the nine units - one was unoccupied - are all staying elsewhere. The fire, which occurred about 12:20 p.m. on a Wednesday, when many residents were away, spread from the cigarette on the deck of apartment number nine, according to the fire department. The fire was ruled an accident. Damage is estimated at more than $1 million.