A five-alarm fire on the top floor of a Hamilton Heights apartment building has sent one firefighter to the hospital—and it's still burning.

The blaze sparked around 3:45 p.m., and has so far called 44 units and 198 responders to the scene at 520 W.139th Street. The cause of the fire remains unknown. "It's still a very active fire," an FDNY spokesperson said.

The injured firefighter was transported to Cornell University Hospital with unspecified minor injuries.