BIRMINGHAM, Ala. (AP) — A fire at an Alabama apartment complex has injured a firefighter and destroyed a four-story building and a law office.

News outlets report a firefighter responding to the early Thursday blaze at a Birmingham apartment was injured and taken to a hospital. The apartment was under construction and had no residents, windows or doors. It was completely covered in flames when responding agencies arrived just after midnight.

Birmingham Fire and Rescue Service Capt. Harold Watson says the fire spread and destroyed a nearby law office that was empty at the time. Around 50 firefighters still were on scene hours later fighting the uncontrolled blaze. Watson says firefighters are expected to remain on scene most of the day.

The cause of the fire is unclear.