Fire officials are investigating the cause of a Christmas morning house fire in eastern Louisville that claimed the lives of two boys, ages 10 and 12.The fire broke out early Friday at the Glenview home of the children's grandparents, Irving and Cathy Bailey. Cathy Bailey was ambassador to Latvia during the George W. Bush administration; Irving Bailey is a longtime Louisville-area businessman.The Baileys were injured in the blaze and hospitalized. Three firefighters suffered non-life threatening injuries.