Investigators are trying to figure out what sparked a ferocious house fire in Port Jefferson Thursday.Flames broke out at the home on Hoyt Lane around 1 a.m. A neighbor noticed the flames and called 911. The homeowner believes an explosion in the back of the house ignited the fire.

The fire destroyed the house but the homeowner, his wife and 4-year-old son escaped unharmed. The family is staying with relatives in the area.