Corpus Christi fire investigators have ruled the fire that claimed the life of an elderly woman Wednesday was accidental.According to neighbor's surveillance video, the fire broke out around 11:18 p.m. and fire trucks arrived at the scene around 11:45 p.m.Fire Marshal Randy Paige told KRIS 6 News fire investigators believe an extension cord started the fire that killed the 71-year-old woman inside.Meanwhile, the Nueces County Medical Examiner's Office has not identified the elderly fire victim. Elderly woman found dead at fatal house fire on Morgan Avenue