Record winds and flooding from superstorm Sandy hammered New York on Monday, killing at least two people and leaving wide sections of the city without power.

The superstorm, which put a huge swath of Manhattan from Midtown to Battery park in darkness, also forced hospital evacuations and left a huge construction crane dangling in the powerful gales 75 stories over a posh thoroughfare.

Mayor Michael Bloomberg called the superstorm, which forecasters downgraded from a hurricane just before it made landfall in southern New Jersey, a "once in a long time storm."

The mayor urged New Yorkers to stay off the streets, warning "the worst of the weather has come."

New York was hit with gale force winds reaching 85 mph and a record 13-foot storm surge, exacerbated by a full moon at high tide.

One man was reportedly killed when a wind-toppled tree crushed his home and a woman was electrocuted by a downed electrical wire, both in the New York borough of Queens, a fire department spokesman told Xinhua.

CBS New York reported three other people were killed outside the city, including two teenage boys, when a tree fell on a house in North Salem, N.Y..

A long string of storm-related incidents began hammering New York on Monday morning and escalated as the wind speed increased throughout the day and the tide rose in the evening.

Several buildings partially collapsed, including the face of a building in the Chelsea section of Manhattan's West Side. There were no injuries.

In addition, the boom of a huge crane was blown back atop its control cab and counterweight at a 90-story luxury residential building under construction on West 57th Street in midtown Manhattan. The boom was left dangling from its precarious perch at a height of 304 meters.

Fire officials ordered buildings in a two-block radius evacuated and gas and steam mains closed down. That came out of concerns that if the hanging boom broke loose it could pierce nearby buildings or the pavement, rupturing gas and steam lines, and sparking explosions.

Late Monday, New York University's Langone Medical Center on Midtown's East Side began evacuating about 200 patients after losing electricity. The evacuees included neo-natal infants, some cradled in the arms of nurses, their intravenous drips attached. The infants had to be carried downstairs because no elevators were working.

Dr. Robert Grossman, dean of the hospital, told CBS's Channel 2 that backup generators failed in the blackout, which stretched from a few blocks north of the hospital all the way to Battery Park near the southern tip of Manhattan.

He said patients were being transferred to Mt. Sinai and Memorial Sloan-Kettering hospitals uptown. Scores of ambulances lined the First Avenue in front of the hospital waiting to ferry the patients to the other hospitals.

"There's a spectrum of illnesses," he said of the "mostly critical-care" patients' ailments. "Some of them are very sick."

A few blocks south of the NYU hospital complex, calls were heard for oxygen tanks and fuel to power Bellevue Hospital's backup generators. National Guard troops were being sought to carry fuel containers up 13 floors to the backup power units.

By Monday night all bridges linking Manhattan and Staten Island with other boroughs in the city and New Jersey were closed, except for the Lincoln Tunnel between midtown Manhattan and New Jersey.

The Brooklyn-Battery tunnel was dramatically flooded in a cascade of water reminiscent of a waterfall pouring in from flooded Battery Park City.

On Sunday night, ferry services to and from Manhattan, including the Staten Island Ferry, were suspended along with all Metropolitan Transportation Authority subway and bus lines in the city. All commuter bus and rail lines also have been suspended since Sunday.

Amtrak, the national passenger rail network, suspended service on the Northeast Corridor through New York City and running between Washington and Boston. Long distance trains through the metropolis were canceled.

John F. Kennedy International and LaGuardia airports in the city were closed, with air travel halted.

UN Headquarters and the New York Stock Exchange were among the institutions and businesses closed Monday, mainly for lack of transportation for workers. They were to be shuttered Tuesday as well.

Subways and bus service was suspended Sunday night, officials said, in order to position them on high ground or in the tubes of subway lines not in danger of flooding. Several subway lines in lower Manhattan were flooded.

Another storm surge was expected at high tide Tuesday morning but it was not expected to be as severe as Monday night's, weather forecasters said.