A child playing with a stove burner accidentally caused the fire in an apartment building in the Bronx, New York City.

On Friday, FDNY Commissioner Daniel Nigro confirmed that a three-year old boy triggered the Bronx fire. It is the deadliest fire in the city in nearly three decades.

In a statement, Nigro said the mother immediately left the apartment with the boy and his younger sibling after the fire erupted. She left the apartment door open, a terrible mistake.  Their apartment was on the first floor of the building.

Unprecedented loss of lives in the Bronx

Nigro said, “The fire quickly spread up the stairs. 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 the stairs. Of those that tried, a few of them perished. Others were helped out onto the fire escapes, taken down by our members.”

Additionally, Nigro said the fire took the lives of 12 people. Four other individuals are in critical condition at local hospitals. He said, “This loss is unprecedented. If unfortunately you do have a fire in your apartment, you must close the door when you exit.”

Video footage of the burned out hallway and stairwell of 2363 Prospect Ave in the Bronx, where a 5th alarm fire killed 12 people. #FDNY Fire Marshals determined the cause of the fire to be a young child playing with the burner on a stove pic.twitter.com/MwcuxX6j8k

— FDNY (@FDNY) December 29, 2017

According to the FDNY, the victims included children (aged 8 months, 1, 2 and 7) and an unidentified boy. The other victims were three women (aged 19, 37, and 63), an unidentified woman and four unidentified men.

Late Friday, the NYPD disclosed the identities of some of the victims including Karen-Stewart Francis and her daughters Kylie, Charmela, and Karen Francis. Her niece Shawntay Young also died.

Ambrozia Stewart, the mother of Stewart-Francis told The New York Times, “I don’t know what to do. I don’t know how to feel. Four at one time—what do I do?”

Terrible tragedy

In an interview with CNN, New York City Mayor Bill de Blasio, said, "This is a terrible tragedy in the middle of the holidays. When people are trying to be with their families and have a moment of peace, finally, and having something like this happen to people in the Bronx is just horrible.”

During a news conference, Mayor de Blasio requested New Yorkers to "hold your families close and keep these families here in the Bronx in your prayers."