Wilmington's Fire Marshal is investigating the cause of a blaze that left a house unlivable Saturday morning. Crews were dispatched to 2306 Delaware Avenue around 7:20 a.m. and found heavy smoke coming from the basement. The firefighters confined the fire to the basement, and the situation was under control in roughly half an hour. The house's occupants got out safely before firefighters arrived. The city's Department of Licenses and Inspections determined the house is uninhabitable.