Two people are dead and at least 20 injured after two apartment buildings in East Harlem partially collapsed following a massive gas explosion earlier today.
Emergency crews and firemen from across New York City rushed to the scene as a large plume of dark smoke fanned across the city following the incident, which happened just as the morning rush hour was coming to an end.
A number of residents are thought to be still trapped in the rubble.
Smoke from the blast was visible within minutes from the bustling heart of commercial Midtown.
Matt Washington, chairman of Community Board 11 which represents East Harlem, told NBC that at least two people had died and 20 were hurt as a result of the blast.
Witnesses, many on their way to work and some still in their apartments, said they had heard a very loud blast from where the apartment building once stood at East 115th St and Park Avenue in Harlem.
New York City Mayor Bill de Blasio said in a news conference that the gas leak had been reported to the utility company just 15 minutes before the blast.
A resident from a building next to the two that collapsed reported that he smelled gas inside his apartment, but thought the odor could be coming from outside, Bob McGee, a spokesman for the utility company Con Edison, said.
He said the utility company dispatched two crews just after 9:15 a.m. but they arrived after the explosion. McGee said the street is served by an eight-inch (20-centimeter) low pressure gas main, but would not speculate on whether a gas leak caused the explosion.
"We're working with the (fire department) and checking gas lines. We're working to isolate any leaks and make the area safe," he said.
Mayor de Blasio said the "major explosion" had destroyed two buildings and heavily damaged other structures.
A car that had been parked outside had also been incinerated.
“It shook my building and I am six blocks south,” one nearby resident told MSNBC News.
“It did feel like a big clap of thunder. It is a little worrying to know the cause.” He said that even though he lives six blocks away from the fire his building was shaken by the explosion.
No fewer than 39 units of the New York Fire Department were sent to the scene, officials said, involving almost 200 firemen.
First glimpses of the site revealed that debris had been spread over a large area, including across the tracks of a main commuter train line into New York from the North and Connecticut. One of the busiest train corridors in the nation, it has been shut down pending the scene being brought under control.
While the neighbourhood is among the most densely populated in New York there was still no early word on numbers of possible victims or indeed whether any residents of the structure or local workers might have been trapped by the collapse.
Mayor Bill de Blasio said preliminary information showed the blast may have been caused by a gas leak.
Investigators will be trying to determine if any work was being done in the vicinity, perhaps on gas lines, in the minutes before it happened. Most of the buildings in this area feature commercial spaces and shops on the street level and then apartments above them.
Another resident of the area spoke of “debris in the air” that he saw rising after hearing the boom. “It looked like like paper and other products”, he said.
Another witness told the New York Daily News: "It was loud, like boom, boom!" Mitch Abreu said. "It rocked the whole block.
"A window blew out of the other shop down the street. It looked like the [Twin] Towers all over again. People covered in dust and covering their mouths."