ABILENE (AP) — Investigators blame a lit cigarette for starting a West Texas house fire that killed an 82-year-old woman and her son.

KTXS-TV reports Abilene Fire Department investigators have determined the July 20 fire was an accident.

Officials say Barbara Cocke was transported to an Abilene hospital, where she was pronounced dead. Her 58-year-old son, Michael Cocke, was flown to Parkland Memorial Hospital in Dallas, where he died hours after the pre-dawn blaze.

Authorities say the fire started in the living room when a lit cigarette was dropped on the carpet, then quickly spread to nearby furniture. Both victims suffered burns and smoke inhalation.

Investigators did not immediately say who was believed to have been smoking.