At least 19 people, including nine children, were killed Sunday in a fire at a Bronx apartment complex caused by a malfunctioning portable space heater, the city’s deadliest blaze in more than 30 years.

The fire “started in a malfunctioning electric space heater” in a bedroom of a duplex apartment on the second and third floors of the 19-story Twin Parks North West complex in New York City’s West Bronx, according to New York City Fire Commissioner Daniel Nigro. The door of the apartment was left open, allowing smoke to quickly spread throughout the building, Nigro said.

Thirteen people remained in critical condition in hospitals as of Sunday evening, according to New York Mayor Eric Adams, who spoke at a press conference. More than a half-dozen people were hurt. Most of the victims had severe smoke inhalation, Nigro added.

The children killed were 16 or younger, according to Stefan Ringel, a senior adviser to Adams. According to Nigro, victims were discovered on every floor of the structure.

Over 200 firefighters were dispatched to the scene, according to the fire department. As of 1:27 p.m. ET, officials said the fire was under control.

According to Nigro, fire marshals determined the space heater was the cause of the fire based on physical evidence and firsthand accounts.

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

However, when a notification appeared on his phone, he and his mother became concerned. 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.

Vernessa Cunningham, another resident, said she rushed home from church after receiving an alert on her cellphone that the building was on fire.

“I couldn’t believe my eyes when I saw what I was seeing. “I was in a state of shock,” Cunningham, 60, said from a nearby school where some residents had gathered. “I was able to see my apartment. The windows were all shattered. And I could see flames coming from the building’s back.”

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

According to Nigro, the Bronx hasn’t seen a fire this “horrific” since the Happy Land fire in 1990, which killed 87 people. The disaster on Sunday was the city’s deadliest blaze since that one.

According to data from the National Fire Protection Association, Sunday’s fire was also the deadliest in a U.S. residential apartment building since 2017, when 13 people died in an apartment building in the Bronx.

Adams praised the firefighters who responded, noting that some of them ran out of oxygen in their tanks while attempting to rescue victims.

“Some of these firefighters had their oxygen tanks empty and were still pushing through the smoke,” Adams said. “You can’t do this unless you feel connected to the city and this community, and I really want to thank them for putting their lives on the line to save lives.”

Adams stated that schools would be open and that people who had been displaced by the fire would be taken there to reconnect with family. He stated that the community was “heavily immigrant,” and that government officials would work to assist affected families in finding temporary and permanent housing.

According to Adams, those seeking assistance will not be turned over to US Immigration and Customs Enforcement.

Senate Majority Leader Chuck Schumer, D-NY, promised to provide as much assistance as possible at the federal level, including housing and tax relief, as well as immigration assistance for those in need.

“When there’s a tragedy, we come together; we don’t care about ideology, race, creed, color, or religion,” Schumer said. “We come together, we embrace one another and we say we are for helping New Yorkers who need help.”

New York Gov. Kathy Hochul said she plans to establish a victim’s compensation fund aimed at providing new housing and covering burial costs for affected families.