Two firefighters and 7 residents were injured in the fire.
One critically injured man reportedly jumped from the burning building and was rushed to Stonybrook University Hospital.
Residents were running for their lives including children who were stuck inside for some time.
Over 100 firefighters battled the blaze but one hydrant did not provide water to get the flames out fast enough.
"The problem is it was a small water main that supplies the complex. We just needed more water," said Chief Rich Huttie of the Central Islip Fire Department.
Officials do not believe the fire was suspicious.
The Red Cross is providing assistance to the dozens of people displaced from their homes.
NEW YORK AND TRI-STATE AREA NEWS
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