This post was originally published on this site

Last Updated Dec 29, 2017 11:37 AM EST

NEW YORK — A four-alarm fire that claimed the lives of at least 12 people in New York City was caused by a 3-and-a-half-year-old boy who was playing with burners on a kitchen stove located in a first-floor apartment, Mayor Bill de Blasio’s office announced Friday. During a news conference, New York Fire Commissioner Daniel Nigro said the boy had a history of playing with the burners and turning them on.

The boy’s mother said she was unaware that he was playing with the stove at the time. When she was alerted by his screaming, she exited the apartment with her children and left the door open, which caused flames to quickly spread up the open stairway, acting like a chimney. 

“Children starting fires is not rare,” Nigro said. “The department has a program to educate children, and we get 75 to 100 referrals a year about children that have issues with playing with fire or being fascinated by fire. It’s not particularly unusual, but very sad.”

“This loss is unprecedented,” he continued. “The lessons here of children left unattended … how dangerous this can be. It saddens our entire department this time of year that our members are carrying out folks, including young children.” 

The blaze erupted Thursday night in the five-story building, located a block from the grounds of the Bronx Zoo. Dangerously fast-moving flames spread throughout every floor of the building within minutes.   

FDNY personnel work on the scene of an apartment fire in New York

Fire Department of New York (FDNY) personnel work on the scene of an apartment fire in Bronx, New York, U.S. December 28, 2017.


Firefighters responded to the scene in just over three minutes. It took several hours for crews to contain the flames. 

Residents who attempted to leave the building through the stairway ultimately perished in the flames, according to Nigro. Other tenants who climbed down fire escapes in freezing cold weather were rescued by firefighters at the scene.

Authorities say the building housed 25 apartments. At this time, all tenants have been accounted for.

The victims who died ranged in age from 1 to 63. Police say a 1-year-old girl, a 63-year-old woman and three unidentified men were pronounced dead at the scene. The other victims — three adults and four children — succumbed to their injuries at various hospitals in the city.

All identities were being withheld pending family notification. 

According to de Blasio, four others sustained critical injuries in the fire. At this time, they remain hospitalized in critical condition, Nigro said.

“This is the worst fire tragedy we have seen in this city in at least a quarter century,” de Blasio said. “Based on the information we have now, this will rank as one of the worst losses of life to a fire in many, many years.”  

Freezing temperatures complicated the firefight inside the roughly 100-year-old building. 

CBS News correspondent Don Dahler reports city records show the apartment building had a number of violations, including a faulty smoke detector on the first floor. Police are working to determine if all smoke detectors in the building were functioning properly when the blaze broke out. 

Authorities are actively investigating the deadly incident. 

© 2017 CBS Interactive Inc. All Rights Reserved.