The FDNY says they are working to determine the cause of a fire at a building on Herzl Street and Pitkin Avenue in Brownsville.

The fire broke out on the first floor of the four-story building just before 9:30 a.m., according to authorities.

The FDNY says three people were injured but refused medical attention.

Firefighters also discovered a lithium-ion battery at the scene. However, authorities say the fire marshal’s office is still investigating the exact cause.