A pilot died when a helicopter crashed onto the roof of a Midtown Manhattan building in a hard landing on Monday, filling the air with smoke and clogging the city streets with fire trucks, according to police and fire officials.
The pilot, Tim McCormack, was the only person on board the privately owned Agusta A109E helicopter, said police and fire officials.
No one else was injured in the crash, which took place in the heart of New York City, just blocks from Times Square, according to city officials.
(MORE: 'I heard a buzz and a bang': Firsthand account of inside the NYC building of crash)It's believed to be an accident and there's no indication of terrorism, a senior official with the Federal Aviation Administration (FAA) told ABC News.
The cause of the "shocking, stunning incident" is unclear, said New York City Mayor Bill de Blasio.
"There is no ongoing threat to New York City," the mayor added.
The hard landing sparked a fire and a fuel leak that have since been stopped, officials said.
(MORE: Helicopter crash in Manhattan's East River kills all 5 passengers, pilot escapes)The crash -- which took place shortly before 1:45 p.m. -- came on a rainy New York afternoon. Both Newark and LaGuardia Airports are in a ground stop due to visibility and thunderstorms, according to the FAA.
"This could have been a much worse incident," the mayor told reporters. "Thank God no other people were injured."
The building -- the AXA Equitable Building -- is located at 787 Seventh Ave., between 51st and 52nd Streets.
It's a busy area of Midtown Manhattan, just below Central Park South, filled with business towers.
The building is roughly between Carnegie Hall and Radio City Music Hall, a few blocks southeast of Columbus Circle and southwest of the Trump Tower on Fifth Avenue.
(MORE: 5 bodies spotted in Himalayas during helicopter search for missing climbers)Shauna Farrell said she was in a meeting on the 36th floor of the building "when a window fell through and we heard a loud whizzing sound of a motor."
Then she said she felt the hard landing, prompting herself and others on the floor to get out of the building.
"We ran down. I think we were the first floor to evacuate, actually, because we felt it so quickly," Farrell told ABC News.
"There was already FDNY on the scene. We were kind of just running away from the building as quickly as we could," she said.
Steven Gartner was on the 42nd floor of the building when he said he heard "a buzz and a bang -- and then the entire building shook."
His colleagues "were anxious," he told ABC News, but all managed to evacuate through the stairwell without panicking.
Though the crash appeared to be accidental, New York Gov. Andrew Cuomo told reporters, "If you're a New Yorker, you have a level of PTSD from 9/11 ... So as soon as you hear an aircraft hit a building, I think my mind goes where every New Yorker's mind goes."
The pilot took off from the 34th Street heliport on the east side of Manhattan and was heading to Linden, New Jersey, officials said.
The hard landing occurred inside an area of Manhattan with flight restrictions that require aircraft to get permission from air traffic control to enter. Many flights originating from the 34th Street heliport do get such permission, but FAA officials told ABC News that air traffic control did not handle this flight.
Cuomo said investigators were looking into why the chopper -- registered to N200BK INC in New York -- was flying in the restricted airspace and if it had permission to do so.
The president is monitoring the situation, according to a White House official.
"Phenomenal job by our GREAT First Responders who are currently on the scene," President Donald Trump tweeted. "THANK YOU for all you do 24/7/365! The Trump Administration stands ready should you need anything at all."
The AXA Equitable Building was built in 1985 and has 51 stories, according to commercial real estate website Compstak. It's home to asset management firms, law firms, a Citibank and a software company, according to the site.
The pilot, McCormack, appears to be the same one involved in a 2014 emergency landing in New York City after an apparent bird strike. There is only one Timothy (or Tim) McCormack with an FAA license to fly helicopters, according to the FAA's airmen database.
"Our family lost a great man today when my brother lost his life doing his job," the McCormack family said in a statement provided to ABC News. "My brother Tim was a professional helicopter pilot who worked in private transit and was a flight instructor as well. He was a caring and compassionate man who put others first over himself. Tim died when in my opinion he put other lives first over his by using his skill as a pilot to emergency land his helicopter on a roof of a building so that it didn't impact anyone else's life except his own. My brother was a true hero."
American Continental Properties Inc, the company the helicopter is registered to, offered their condolences in a statement.
"We are mourning the loss of Tim McCormack who has flown for us for the past five years. Our hearts are with his family and friends," the statement read.
ABC News' Jeff Cook, Julia Jacobo, Morgan Korn and Meghan Keneally contributed to this report.