The fire broke out at 3435 Dekalb Ave., between Kossuth Avenue and East 208th Street, just before 6 a.m.
Fire officials say they believe the fire had been burning for quite some time before residents noticed it.
The fire broke out on the top floor of the building and spread to the cockloft.
Firefighters encountered several complications while battling the blaze. Officials say blown-in insulation in the building held in heat and smoke, while two cars blocking a fire hydrant made it difficult for firefighters to get water into the building faster.
Roughly 75 Fire and EMS units responded to the scene.
Two residents and two firefighters suffered minor, non-life-threatening injuries.
One resident told Eyewitness News he lost everything in the fire.
This is a developing story.
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