WAPPINGER — Investigators say spontaneous combustion of sawdust in a floor sander's dust collection bag caused a house fire that killed a 7-year-old boy last summer in upstate New York.The Poughkeepsie Journal reports Dutchess County fire investigators ruled the August fire in Wappingers Falls was accidental. The fire killed 7-year-old Sean Burlingame.The boy's mother, Dina Pinera, told investigators she and her boyfriend had been working on refinishing the dining [...]