A fire that broke out on Sunday in an apartment building in the Bronx borough of New York City left 19 people, including 9 children, dead as dozens of others were injured, some critical, in what the city's fire commissioner called one of the worst blazes in recent memory.

A fire official who was not authorized to speak publicly confirmed the death toll Sunday to The Associated Press (AP), while a city official who was not authorized to speak publicly confirmed the number of children dead.

Dozens of people were injured in the Bronx fire, and at least 32 people were hospitalized. According to the New York City Fire Department (FDNY), approximately 200 firefighters responded to the scene Sunday at the Twin Park apartments, a 19-story building on East 181st Street. Photos posted online showed a rescue ladder extended up to an eighth-floor window.

Thirty-two people were transported to five hospitals, with the majority of the victims suffering from severe smoke inhalation, FDNY Commissioner Daniel Nigro said.

Firefighters "found victims on every floor and were taking them out in cardiac and respiratory arrest," he said. "That is unprecedented in our city. We expect there to be numerous fatalities."

Nigro compared the severity of the fire to the Happy Land social club fire, which killed 87 people in 1990 when a man set fire to the building after getting into an argument with his former girlfriend and being thrown out of the club.

According to Nigro, Sunday's fire originated in a duplex apartment spanning the second and third floors. Firefighters found the door to the apartment open, he said, which apparently allowed the fire to accelerate and spread smoke upward quickly.

The fire is not believed to be suspicious in origin but the cause is under investigation.

Sunday's fire comes just days after a house fire in Philadelphia left 12 people – including eight children – dead.