A 42-year-old man and two children -- boys ages 5 and 5 months -- were critically injured after being overcome by smoke in an attempt to escape the building.
Also among the injured victims are six firefighters.
The flames broke out in an apartment building in the Bath Beach section around 6:30 a.m. Wednesday.
According to fire officials, a family fleeing the fire in their apartment left their front door open, which allowed smoke to billow into the hallway and throughout the building.
Multiple people were apparently trapped in building stairwells as a result with heavy smoke impeding their exit.
"Firefighters were confronted with the biggest challenge we always have, the fire door, the apartment was left open," Joe Duggan, FDNY Deputy Assistant Chief, said.
"If you leave the fire door open, that causes all sorts of problems. And not for the people in the apartment directly involved, but for their neighbors that were found upstairs. They were the victims we had to transport to the hospital."
The fire could be seen in multiple apartments between the second and third floors.
The injured children were taken to Maimonides Medical Center to be treated in the pediatric unit, while the adult was taken to Coney Island Hospital.
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