Fire crews battled an early morning Thursday fire on the fourth floor of an apartment in Brooklyn.

Citizen App video from the scene show firefighters responding to 7th Street at 4th Avenue around 1 a.m.

FDNY says at least one person has critical injuries, and three firefighters were evaluated for minor injuries.

The fire was placed under control around 2:30 a.m.

The fire marshals say the cause is still under investigation.