ROCKFORD (WIFR) -- The cause of a house fire in Rockford remains under investigation Thursday morning.

Upon arrival, Rockford fire officials say they were able to see flames in a home in the 900 block of 6th Avenue just after 5 a.m. Crews lay a working line to protect exposures. Crews called it a defensive fire. No injuries were reported. About $15,000 is estimated in damage.