A helicopter has crashed on the roof of a high-rise building in New York City, local officials say.

At least one person, believed to be the pilot, was killed, a senior NYPD official said.

The accident happened just before 2 p.m. on Monday when the aircraft crashed or crash-landed on the top of 787 7th Avenue in Midtown Manhattan. It happened at a 54-story office building.

The New York Fire Department confirmed the crash and declared a 2-alarm incident, but details about injuries were not immediately known. It’s unclear what type of aircraft is involved and how many were on board.

“We felt a jolt in our building and shortly after got the instruction to evacuate,” one worker at the building said. Thousands of people have been evacuated from the building.