NEW YORK — (CNN) One person was killed and three others injured when a 565-foot crane collapsed during Friday morning’s rush hour in snowy Lower Manhattan, authorities said.

The lone fatality was a person sitting in a parked car, and the three injuries — two considered serious — occurred when pedestrians were hurt by falling debris, Mayor Bill de Blasio told reporters.

The crawler crane was being lowered into a secure position, with construction workers keeping pedestrians and traffic away from a busy street near New York Law School, when it hurtled to the ground, de Blasio said.

The crane’s manufacturer required that it be secured when winds reached 25 mph, the mayor said.

“You can see how powerful the damage was, but you can also see that it was something of a miracle” there were not more casualties, de Blasio said.

As a precaution, the city immediately ordered the 376 crawler and 43 tower cranes in operation in New York be immediately secured, officials said.

Building inspectors had been at the site of the collapse a day earlier after granting approval for the crane operator to add an extension — bringing the crane to 565 feet, according to de Blasio.

The impact of the hulking crane may have caused damage to some underground gas mains, and utility inspectors were checking for gas leaks, officials said.

Some residents said the impact resembled an earthquake, momentarily causing the ground to shake.

“The fact is this is a very,very sad incident. We lost a life,” de Blasio said. “Thank God it was not worse.”

The cause of the collapse was being investigated by police and building department officials.

The crane was being used to replace generators and air conditioning equipment on the roof of a building on Hudson Street, officials said. The work started on January 30.

Some buildings in the immediate area were evacuated because of the possibility of gas leaks as well parapets that were in danger of collapsing, fire officials said.

Twitter lit up with images showing the towering crane lying on a city street, crushing some cars, as first responders rushed to the scene.

Some showed the crane, including its tracks, upside down with its boom resting alongside several buildings.

The fire department dispatched 33 units with 138 personnel to the scene at 40 Worth St. and West Broadway after the crane collapsed shortly before 8:30 a.m.

New York Law School evacuated its campus and canceled classes until Monday due to the collapse, spokeswoman Silvia Alvarez said.

It’s not immediately known what caused the collapse.

New York was under a winter weather advisory Friday morning, with the forecast calling for snow and sustained winds between 16 mph and 18 mph, and gusts as strong as 29 mph, according to the National Weather Service.

But city officials said snow did not appear to be a factor.

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