HOUSTON --
Fire investigators think they know what started a fire that killed two young brothers. The Harris County fire marshal say it appears one of the boys was playing with a lighter and a piece of paper when they accidentally set their couch on fire. The Monday afternoon fire killed nine-year-old Tristan Huff and his six-year-old brother, Timothy. Family members say the boys were autistic. Their mother, Mary Ann King, suffered burns to her arms trying to save her sons. A third son escaped the fire unharmed. The mother is in fair condition.