A firefighter suffered minor injuries early Wednesday battling a fire in a vacant northwest Atlanta home that quickly spread to an occupied home next door.

The blaze broke out around 3:30 a.m. in the 600 block of Joseph E. Boone Boulevard near Sunset Avenue.

Atlanta fire Battalion Chief Monterio Stidwell said the fire apparently started in a vacant home that had been boarded up. That house was fully-engulfed in flames when firefighters arrived, and the fire had already spread to the house next door.

One firefighter was taken to Grady Memorial Hospital for treatment of burns to his shoulder, according to Stidwell.

“Crews were making an interior attack on the occupied structure to search for an occupant and he received second-degree burns,” Stidwell told The Atlanta Journal-Constitution.

Fire crews found no one at home during the searches of the occupied house, and no other injuries were reported, Stidwell said.

The cause of the fire is under investigation.