What you need to know:
- Emergency services fanned out around the 54-story building on Seventh Avenue after what was described as a "hard-landing" by a chopper that took off barely 10 minutes earlier from a heliport in the city.
- The pilot was the only person on board the chopper, according to US aviation regulators.
- The city fire department urged people to avoid the area.
A helicopter crash-landed on top of a high-rise in midtown Manhattan Monday, starting a fire and leaving one person dead as the entire building shook from the impact.
Emergency services fanned out around the 54-story building on Seventh Avenue after what was described as a "hard-landing" by a chopper that took off barely 10 minutes earlier from a heliport in the city.
The New York fire department confirmed one fatality -- presumed to be the pilot, according to Mayor Bill de Blasio.
Speaking at the scene, de Blasio said it "could have been a much worse incident."
PLUME OF SMOKE
"There were no other injuries that we know of at this point in time to anyone in the building or on the ground," he said: adding: "Thank God for that."
The pilot was the only person on board the chopper, according to US aviation regulators.
"There is no indication at this time that this was an act of terror," said de Blasio. "And there is no ongoing threat to New York City based on all the information we have right now."
Video footage of the aftermath of the crash showed a gray plume of smoke drifting away from the top of the building.
The city fire department said it had extinguished a fire on the building's roof -- the height of which posed a challenge to firefighters.
"Whenever we have a fire on a high-rise office building -- 54 stories is over 700 feet tall -- we have challenges getting enough water pressure up to the higher levels of the building," Chief of Fire Operations Thomas Richardson was quoted as saying in a post on the New York fire department's Facebook page.
Nathan Hutton, who works in the building on the 29th floor, said he had "felt the whole building shift."
"We thought it was an earthquake or something like that," he told AFP. "Something small like that. Then two minutes after, the alarms went off and then security came in: 'Everybody just grab your bag and walk out the door now!'"
He said there was no panic, but going down the stairs "was scary because everybody from all the floors" was descending "all at the same time" -- a process that took half an hour.
"There was no shouting but a little nervousness, with the occasional, 'C'mon, move!" he added.
The Federal Aviation Administration (FAA) identified the chopper as an Agusta A109E and said the crash occurred about 1:45 pm (1745 GMT).
The National Transportation Safety Board "will be in charge of the investigation and will determine the probable cause of the accident," the FAA tweeted.
President Donald Trump said he had been kept informed of the situation.
"I have been briefed on the helicopter crash in New York City. Phenomenal job by our GREAT First Responders who are currently on the scene. THANK YOU for all you do 24/7/365! The Trump Administration stands ready should you need anything at all," Trump tweeted.
The city fire department urged people to avoid the area.
Five people died after a helicopter plunged into Manhattan's east river near the upscale Upper East Side neighbourhood in March 2018.
The chopper, which was owned by tourism group Liberty, was carrying six people including the pilot, who managed to free himself. The other five did not.
That crash led US aviation authorities to review regulations for so-called "doors off" flights, which provide passengers with a more direct view of the skyline than flights with the aircraft's doors shut.