A blaze that claimed the lives of a couple and their three children in a Manhattan apartment was caused by a child playing with a lighter or matches, authorities said Monday.

The couple's 10-year-old son survived the fire Saturday, but remained hospitalized with critical injuries.

Fire officials say another fatal fire on Sunday in a Brooklyn apartment was caused by a candle. It took the lives of a Guyanese immigrant and his 12-year-old nephew.

All seven victims died of smoke inhalation, said Ellen Borakove, a spokeswoman for the city medical examiner's office. There were no working smoke detectors in either apartment, authorities said.

In Saturday's fire, six members of one family were found unconscious, huddled in the bathroom and bedroom of their apartment in Manhattan's Chelsea neighborhood. Only the boy survived.

Neighbors told fire authorities that the children had a history of playing with lighters or matches, and firefighter Alejandro Bartley said fire marshals determined that the fire was fueled by papers on the kitchen table. A lighter or matches were recovered in the area, he said. No appliances were plugged in and there were no outlets nearby.

Jacobi Medical Center declined to provide an update on his condition Sunday evening, citing privacy laws. Fire officials said earlier that the boy was in critical condition, placed in a hyperbaric chamber that supplies emergency oxygen to burn victims.

The fire was the city's deadliest since a March 2007 blaze in the Bronx killed 10 people, including nine children, officials said.

The fire started at about 6:30 a.m. in the kitchen of the family's home in the Robert Fulton public housing complex. Thick, black smoke quickly filled the apartment and kept the six from escaping through the front door, fire officials said. There was no fire escape.

"I smelled smoke and heard bodies slamming and yelping — yelping like a dog," Tashara Francis, who lives on the floor below, told the Daily News.

The Fire Department said the apartment's smoke detector had been unplugged and its battery removed. The smoke detector was inspected six months ago and was working, according to New York City Housing Authority officials.

A working alarm might have alerted the victims in time in time for them to flee, deputy fire chief James Daly said.

Saturday's victims were identified as the 40-year-old father, Maschay Joa Valdez, the 34-year-old mother, Delkis Balbuena; and three girls, 8-year-old Nancy Joa Balbuena, 2-year-old Bet-el Joa Balbuena, and Ruth Joa Balbuena, 15 months.

Police did not release the name of the 10-year-old boy. Neighbors identified him as Jonzan Joa Balbuena and said he and his family were immigrants from the Dominican Republic.

Officials say the Brooklyn apartment that was the site of Sunday's fire had no smoke detectors.

Sunday's blaze was reported shortly after midnight in Brooklyn's Bushwick neighborhood. The fire killed Shawn Monderson, 33, and Cemioni Fraser, 12, the medical examiner's office said. Relatives said the two moved into the row-house apartment just last week.

Cemioni, Monderson's nephew, was living with his uncle because his mother had returned to Guyana, the family said.

"It's a family tradition that we look out for each other," Frederick Monderson, the bus driver's uncle, told the Daily News. Shawn Monderson had recently become a U.S. citizen, his uncle said.

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