FDNY officials say the fire started just before 3:40 p.m. at a six-story apartment building at 2609 Bainbridge Ave. and East 193rd and 194th streets in the Fordham section.
A neighbor told Eyewitness News the broke out in the second-floor apartment of a mother, who was home alone with at least four children.
"The mother ran out of her apartment screaming, 'fire, fire,' as flames shot from the second-floor window," said a neighbor named Manuel.
Manuel says the woman had one child with her, but there was too much smoke between her and her three youngest. She needed help finding them.
Manuel said he tried. He said it was so hot, and very smoky. He opened the door, but said the smoke was overpowering.
It would take firefighters battling through the smoke that had filled the hallway to get the three small children out. They were in critical condition.
A delivery worker captured the efforts to revive one of them on the sidewalk.
"I felt really sad because they have three kids. I think maybe one of the kids died. I feel sad," Radi Obad said.
The children were taken to St. Barnabas, but the youngest child, just 1 years old, died. The two other children, believed to be 6-year-old twins, remain in critical condition.
Two adults and three firefighters are also recovering from non-life-threatening injuries.
More than 20 units, and 80 fire and EMS personnel responded to the scene, placing the fire under control about an hour later around 4:40 p.m.
FDNY officials believe that doors left open as occupants fled may have helped the fire spread, as has been the case in several recent fires in New York City.
"We've had several of these fires lately where the occupants of the fire apartment have fled the building and left the fire apartment open. That appears to be the case here again," said FDNY Chief of Operations Malcolm Moore.
While closing the door may not have changed the tragic outcome in that apartment, officials say it would have prevented the oxygen-hungry flames from sweeping up the hallway, causing more injury and damage.
"The minute you close the door, you give everyone else in the building an opportunity to flee, and you give yourself more time to flee in not allowing the fire to chase behind you," Moore said.
The American Red Cross says they have registered 38 people for emergency assistance.
The cause of the fire is under investigation.
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