Some residents jumped from windows to escape the flames, while others were rescued while dangling from their ledges.
The fireball tore through the large apartment complex in Bay Shore, injuring 10 people and leaving residents of 20 apartments homeless.
Numerous residents were hanging out the second-floor windows when firefighters arrived at the Mid-Island Apartments on Union Boulevard just after midnight.
Heavy flames quickly spread through the the second floor and shot through the roof of the structure.
Anthony Rosario and his 61-year-old mother were forced to jump from their window. He landed safely, but his mother was seriously hurt in the fall and was rushed to the hospital. The resident who lived in apartment 2C, where the fire broke out, was transported to the burn unit at Stony Brook University Medical Center.
Firefighters set up ladders and rescued three others from their windows on the courtyard side.
In all, four residents were treated for injuries. Four police officers who spotted the flames and rushed to the scene were also hurt. Two firefighters were hospitalized with heat exhaustion.
The fire started at the north end of buildings and tore through the second floor of the complex.
The Red Cross was finding shelter for eight of the displaced families. Others found their own housing.
The cause of the fire is under investigation.