NEW YORK >> A malfunctioning space heater sparked a fire that filled a Bronx apartment building with thick smoke, killing 19 people, including nine children, today in New York City’s deadliest fire in three decades.

Fire Commissioner Daniel Nigro said the fire “started in a malfunctioning electric space heater” in an apartment unit spanning the second and third floors of the 19-story building. The door of the apartment was left open, allowing smoke to quickly spread throughout the building, Nigro said.

Some residents, trapped in their apartments, broke windows for air and stuffed wet towels under their doors. One man rescued by firefighters said he’d become numb to fire alarms because of frequent false alarms.

Some residents “could not escape because of the volume of smoke,” Nigro said. Firefighters “found victims on every floor and were taking them out in cardiac and respiratory arrest,” he said, calling it “unprecedented.”

Stefan Ringel, a senior adviser to Mayor Eric Adams, said the children killed were 16 years old or younger. Many of the building’s residents were originally from the West African nation of Gambia, Adams said, and there was a large Muslim community.

Thirteen people remained hospitalized in critical condition, Ringel said. In all, more than five dozen people were hurt. Most of the victims had severe smoke inhalation, Nigro said. Adams called the toll “horrific.”

Approximately 200 firefighters responded to the building on East 181st Street around 6 a.m. Hawaii time today.

News photographers captured images of firefighters entering the upper floors of the burning building on a ladder, multiple limp children being given oxygen after they were carried out and evacuees with faces covered in soot.

Building resident Luis Rosa said he was awakened by a fire alarm, but dismissed it at first, thinking it was one of the building’s periodic false alarms.

But when a notification popped up on his phone, he and his mother began to worry. By then, smoke began wafting into his 13th-floor apartment and he heard sirens in the distance.

He opened the front door, but the smoke had gotten too thick for an escape, he said.

“Once I opened the door, I couldn’t even see that far down the hallway,” Rosa told the Associated Press. “So I said, OK, we can’t run down the stairs because if we run down the stairs, we’re going to end up suffocating.”

“All we could do was wait,” he said.

Another resident, Vernessa Cunningham said she raced home from church after getting an alert on her cellphone that the building was on fire.

“I couldn’t believe what I was seeing. I was in shock,” Cunningham, 60, said from a nearby school where some residents gathered. “I could see my apartment. The windows were all busted out. And I could see flames coming from the back of the building.”

The 120-unit building in the Twin Parks North West complex was built in 1973 as part of a project to build modern, affordable housing in the Bronx.

The drab brown building looms over an intersection of smaller, aging brick buildings overlooking Webster Avenue, one of the Bronx’s main thoroughfares.

By Sunday afternoon, all that remained visible of the unit where the fire started was a gaping black hole where the windows had been blown out. Apartments as high as the 12th floor also had broken windows. The intersection was choked with police and fire vehicles, and onlookers were still snapping cellphone pictures of the structure as darkness fell.

“There’s no guarantee that there’s a working fire alarm in every apartment, or in every common area,” U.S. Rep. Ritchie Torres, a Democrat who represents the area, told the AP. “Most of these buildings have no sprinkler system. And so the housing stock of the Bronx is much more susceptible to devastating fires than most of the housing stock in the city.”

Nigro and Torres both compared the fire’s severity to a 1990 blaze at the Happy Land social club where 87 people were killed when a man set fire to the building after getting into an argument with his former girlfriend and being thrown out of the Bronx club.

Sunday’s death toll was the highest for a fire in the city since the Happy Land fire. It was also the deadliest fire at a U.S. residential apartment building since 2017 when 13 people died in an apartment building, also in the Bronx, according to data from the National Fire Protection Association.

That fire started with a 3-year-old boy playing with stove burners and led to several law changes in New York City, including having the fire department to create a plan for educating children and parents on fire safety and requiring certain residential buildings to install self-closing doors.

Sunday’s fire happened just days after 12 people, including eight children, were killed in a house fire in Philadelphia. The deadliest fire prior to that was in 1989 when a Tennessee apartment building fire claimed the lives of 16 people.