Hurricane Sandy hurled crippling floods onto New York streets Monday, provoking a power plant explosion that blacked out much of Manhattan and leaving widespread storm devastation.

The "Frankenstorm" left at least one person dead in America's biggest city, while emergency services rescued many people trapped in their homes. A hospital had to move patients when it lost power.

Seawater burst the banks of the East and Hudson rivers, submerging road and subway tunnels. Power was cut to about 500,000 homes across New York City's five boroughs, including 250,000 in Manhattan.

Gale force winds pushed over a crane on a skyscraper and tore off the facade of another building.

A falling tree killed a man in the Queens borough, firefighters said. Many people had to be rescued from the upper floors of their homes after ignoring pleas to flee zones at risk from floods, officials said.

"I am seriously concerned for people's lives," said Vincent Ignizio, a Staten Island councilor. Police appealed for boats to stage rescues on Staten Island and at Coney Island in Brooklyn as the floods slowly receded.

Four other dead were reported in New York state outside the main city.

The hurricane whipped up a record storm surge of 13.7 feet (4.15 metres) and seawater inundated the key Queens Midtown and the Battery Park-Brooklyn tunnels which take traffic from Manhattan Island to nearby suburbs.

The water threatened to engulf the building site at the World Trade Center where the September 11, 2001 attacks took place.

Many cars in the financial district were swamped, some in New York suburbs were swept away. Debris crushed some cars.

The Con Edison power company said 500,000 homes in New York City were without power. Company vice president John Miksad told reporters it could take a week to completely restore power.

He blamed floods or flying debris for an explosion at a sub-station on the east side of Manhattan's Midtown at the height of the storm. Film of the explosion has been widely viewed on YouTube.

Much of lower Manhattan was blacked out after the explosion. New York University's Tisch hospital had to move 215 patients to other hospitals after it lost power and a back-up generator.

"We went up to 14 foot tides, which no-one was forecasting," Miksad said.

Howling winds of up to 95 miles (150 kilometers) an hour battered the city, pushing over a crane atop a 1,004 (306 metre) luxury apartment skyscraper overlooking Central Park.

The boom of the crane swayed in the fierce gusts and police evacuated surrounding buildings and streets because of the risk that it could fall.

In another spectacular demonstration of its power, the hurricane pulled off the facade of a three-story building in the Chelsea district. No injuries were reported however.

Tens of thousands of people ignored appeals by the New York mayor to leave districts at risk where police had toured the streets calling for inhabitants to take special buses to safety.

Authorities issued a mandatory evacuation order for 375,000 people at risk, but the majority decided to brave it out.

New York state called up 2,100 National Guard troops on Sunday and Monday to patrol threatened districts.

"If water is coming into your home, go to the highest area," New York mayor Michael Bloomberg told a press conference amid the worst of the carnage.

Bloomberg said the public was making 10,000 emergency 911 calls every 30 minutes and appealed to New Yorkers to not just to report power cuts. "It means that genuine emergencies are not being answered," he said.

He also called for taxis to stay off the roads to give priority to emergency vehicles.

New York authorities closed the subway train system and nearly all tunnels and bridges that take traffic off Manhattan as the full force of Sandy hit America's biggest city.

The subway was to remain closed on Tuesday, along with schools, public buildings.