A family of five, including three children as young as 15 months, died in a blaze Saturday that filled an apartment with thick black smoke and kept the victims from escaping through the front door, fire officials said.

A 10-year-old boy who survived was in critical condition after the fire in a public housing complex in Manhattan's Chelsea neighborhood. The boy was found with two other family members in a back bedroom, while the rest of the family sought refuge in a full bathtub and underneath a bathroom sink, officials said.

The cause of the fire, which began in the kitchen of the sixth-floor apartment, was under investigation. But the Fire Department said the apartment's smoke detector had been unplugged and the battery removed.

The smoke detector was inspected six months ago and was working, the New York City Housing Authority said.

Killed were a 40-year-old man, Maschay Joa Valdez; Delkis Balbuena, a 34-year-old woman; and three girls, Nanny Joa Balbuena, 8, Bet-El Joa Balbuena, 3, and Ruth Joa Balbuena, 15 months. The 10-year-old boy was not identified.

The boy was at a hospital, enclosed in a chamber that supplies oxygen to burn victims, fire officials said.

Firefighters worked quickly, shattering windows and extinguishing flames about 45 minutes after the blaze began at 6:30 a.m. on the top floor of a building in the Robert Fulton Houses.

The fire began in the kitchen, close to the front door, Deputy Fire Chief James Daly said.

"The fire didn't allow them to get past to that door," Daly said. "They were trapped in the rear."

Kathy Creer, who lives one floor below, said she knocked on the family's door after a neighbor told her about the blaze. "I was banging, but I heard nothing, no noise," she said.

The hallway was hazy from the smoke, which poured from underneath the apartment door, she said.