Video: Bronx apartment building fire escalates to fifth alarm as FDNY battles massive blaze

BRONX, N.Y. — A major apartment building fire along East 209th Street in the Bronx has escalated to a fifth-alarm fire, with FDNY firefighters continuing to battle the blaze.

The fire, which authorities previously said was sparked by an exploding lithium battery, has prompted a large-scale emergency response, with numerous fire units operating at the scene.

Searches of the building have been ongoing as firefighters work to contain the fire and ensure all occupants are accounted for.

The extent of any injuries has not yet been announced, and the cause of the fire remains under investigation.