The fire broke out just after 5 a.m. in the Red Hook East Housing Development off of Columbia Street.
NewsCopter 7 was over the scene where you could see heavy damage to an apartment on the fifth floor of the building.
The flames were extinguished about an hour and a half later, but firefighters were still searching inside the building.
Two residents were taken to the hospital.
One firefighter was hospitalized and another was checked out at the scene.
Residents were evacuated into the courtyard of the building.
The cause of the fire is under investigation.
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