Maui fire officials are investigating the cause of a house fire that killed a 77-year-old woman Friday morning.  The fire was reported at 5:44 a.m. on Kanani Road, just off Piilani Highway in Kihei.  When firefighters arrived, the fire had consumed half the house.  They brought the fire under control at 7 a.m. and that's when they discovered 77-year-old Hazel Jones.  Her death was classified an unattended death.  Damage to the house was estimated at $300,000.  The cause of the fire was accidental.