A fire at an apartment building in the New York City borough of the Bronx has left at least 17 people dead, Mayor Eric Adams said. 

The death toll was initially reported at 19, but the mayor revised the death toll on Monday.

The city's fire officials said the blaze on Sunday, which was started by an electric heater, is one of the worst blazes in recent memory.

What we know so far

At least 17 people have died, said Mayor Adams, adding that eight of the victims were children.

The fire started from a space heater in an apartment that spanned both the second and third floors, and only made it as far as the hallway, officials said.

But smoke still spread to every floor, probably because the door to the apartment where the blaze began was open, the city's fire department commissioner, Daniel Nigro, told reporters at a news conference.

"This is going to be one of the worst fires in our history," Adams said in an interview with CNN.

Emergency crews said around 60 people were injured in total, while more than a dozen are in hospital and in a critical condition.

The fire broke out at a 19-story building in the Bronx around 11 a.m. (1600 GMT), with the blaze quickly spreading throughout.

Around 200 firefighters responded to the scene at East 181st Street , the city's fire department said, where they discovered victims on every floor of the building.

"Members found victims on every floor in stairwells and were taking them out in cardiac and respiratory arrest," fire department commissioner Nigro said at a press conference earlier on Sunday.

Many of the victims were suffering from smoke inhalation.

How did the fire start?

Fire Commissioner Nigro said that the blaze was caused by a malfunctioning electric space heater.

The fire quickly spread through the duplex unit that the heater was in — climbing up the second and third floors.

The door to the apartment where the fire began was left open — causing a thick cloud of smoke to spread throughout the apartment building.

He added that there were smoke alarms located throughout the building.

Some of the residents who were trapped in their apartments broke open their windows in an effort to get air. Other stuffed wet towels under their doors to block the smoke.

Nigro said earlier that the smoke was so dense that it was "unprecedented."

'Tragedy beyond measure'

New York City Mayor Adams, who has officially been in the job for a little over a week, paid tribute to the victims.

"It's a tragedy beyond measure," Adams said in a message posted on Twitter.

"Join me in praying for those we lost," he added, remembering especially the children whose "innocent young lives ... were cut short."

Update, January 10, 2022: New York Mayor Eric Adams released an updated death toll, saying the total death toll was 17, and not 19 as reported on Sunday. This story has been updated to reflect this change.

jsi, rs/wd (Reuters, AP, AFP, dpa)