A child playing with a stove caused the fire in a New York City apartment building that killed 12 people, including four children, Fire Commissioner Daniel Nigro said Friday, the morning after the fast-spreading fire in the Bronx.
"We found this fire started in a kitchen on the first floor. It started from a young boy, 3½ years old, playing with the burners on the stove," he said at a news conference.
The mother, who was at home, left the apartment with the boy and a two-year-old child, but left the door open, Nigro said.
"Fire travels up; the stairway acted like a chimney. It took the fire so quickly upstairs that people had very little time to react. They couldn't get back down. Those that tried, a few of them perished."

Fire Department of New York personnel work on the scene of the fire in the Bronx. (Kena Betancur/AFP/Getty Images)
The fire, New York City's deadliest residential fire in a quarter of a century, broke out a little before 7 p.m. ET Thursday and spread through every floor of the century-old Bronx apartment building within a matter of minutes, city officials said.
Residents tried to scramble down fire escapes and out into the cold, but not all made it.
The New York Police Department's office of public information said the dead included girls aged one, two and seven, and an unidentified male child.
"It is an unspeakable tragedy, and families have been torn apart," New York City Mayor Bill de Blasio said late Thursday.
Tonight in the Bronx we've seen the worst fire tragedy in at least a quarter of a century. It is an unspeakable tragedy, and families have been torn apart. pic.twitter.com/0kCFMzxt79
—
@NYCMayor
Authorities said firefighters rescued 12 people from the building and four were in the hospital in critical condition. More than 160 firefighters responded to the five-alarm blaze.
Nigro called the fire "historic in its magnitude," because of the number of lives lost. Excluding the Sept. 11 attacks, it was the worst fire in the city since 87 people were killed at a social club fire in the Bronx in 1990.
"In a department that's certainly no stranger to tragedy, we're shocked at this loss," he said on Twitter.
Open building code violations
The building, with 26 apartments, has at least six open building code violations, according to city records. One violation was for a broken smoke detector in an apartment on the first floor that was reported in August. It was not clear if the detector had been fixed or replaced or whether it had played any role in the fire.
Nigro said all the units in the building had fire alarms installed, but investigators were still trying to determine whether all of them were working.

Evacuees wear blankets as they stand outside after the fire sent them fleeing out into the frigid night. (Amr Alfiky/Reuters)
The building is in the Belmont section of the Bronx, a primarily residential, close-knit neighbourhood known as the Little Italy of the borough, near Fordham University and the Bronx Zoo.
It was the deadliest fire in the city since an arsonist torched a Bronx nightclub in 1990, killing 87 people inside the venue that did not have fire exits, alarms or sprinklers, the New York Times reported.
In 2007, 10 immigrants from Mali, including nine children, died after a space heater caught fire in a Bronx building.