A weakened but still dangerous Hurricane Irene shut down New York and menaced other cities as it roared up the East Coast, unloading a foot (30 centimetres) of rain on North Carolina and Virginia and knocking out power to 2 million homes. At least eight people were killed.

The hurricane slammed into the New Jersey shore with 75 mph (120 mph) winds early Sunday as New York emptied its streets and subways and waited with an eerie quiet. Irene had an enormous wingspan — 500 miles (805 kilometers) — and threatened a swath of the nation inhabited by 65 million people.

"The time for evacuation is over. Everyone should now go inside and stay inside," New York Mayor Michael Bloomberg warned late Saturday.

The National Hurricane Center said Irene was 100 miles (160 kilometres) south-southwest of New York City, moving north-northeast at 18 mph (30 kph). It was already stirring up seven-foot (two-metre) waves. A 3.5-foot (1-metre) storm surge hit New York Harbor early Sunday, even with the storm hours away.

Tornadoes were reported in Maryland and Delaware, and several warnings were issued elsewhere, including New York and Philadelphia.

Irene made landfall just after dawn Saturday near Cape Lookout, North Carolina, at the southern end of the Outer Banks. Shorefront hotels and houses were lashed with waves, two piers were destroyed and at least one hospital was forced to run on generator power.

"Things are banging against the house," Leon Reasor said in the town of Buxton, North Carolina. "I just hate hurricanes."

More than 1 million homes and businesses lost power in Virginia alone, where three people were killed by falling trees, at least one tornado touched down and about 100 roads were closed. Eastern North Carolina got up to 14 inches (35 centimetres) of rain, according to the National Weather Service. Virginia's Hampton Roads area was drenched with at least nine inches (23 centimeters), and up to 16 inches (40 centimetres) in some places.

North Carolina Gov. Beverly Perdue said Irene inflicted significant coastal damage, but some areas were unreachable because of high water or downed power lines.

By early Sunday, the storm had sustained winds of 75 mph (120 kph), down from 100 mph (161 kph) on Friday. That made it a Category 1, the least threatening on a 1-to-5 scale. But the storm was still considered highly dangerous, capable of causing ruinous flooding across much of the East Coast due to storm surges, high tides and up to a foot (30 centimetres) of rain.

A nuclear reactor at Maryland's Calvert Cliffs went offline automatically when winds knocked off a large piece of aluminum siding late Saturday night. Constellation Energy Nuclear Group spokesman Mark Sullivan said the facility and all employees were safe.

Irene was the first hurricane to make landfall in the continental United States since 2008, and came almost six years to the day after Katrina ravaged New Orleans. Experts say Irene is threatening more people than any other hurricane in U.S. history.

In New York, authorities undertook the Herculean job of bringing the city to a halt. The subway began shutting down at noon, the first time the system was closed because of a natural disaster.

On Wall Street, sandbags were placed around subway grates near the East River because of fear of flooding. Tarps were spread over other grates. Construction stopped throughout the city, and workers at the site of the World Trade Center dismantled a crane and secured equipment.

The New York area's major airports — LaGuardia, Kennedy and Newark — shut down at noon Saturday. Professional sports events were postponed and Broadway theatres were dark.

New York has seen only a few hurricanes in the past 200 years. The Northeast is much more used to snowstorms — including a blizzard last December, when Bloomberg was criticised for a slow response.

Airlines canceled 9,000 flights, including 3,000 on Saturday. The number of passengers affected could easily be in the millions because so many flights make connections on the East Coast.

In Philadelphia, Mayor Michael Nutter declared a state of emergency, the first for the city since 1986, when racial tensions were running high. "We are trying to save lives and don't have time for silliness," he said.

The storm hit Washington just days after an earthquake damaged some of the capital's most famous structures, including the Washington Monument.

In New Jersey, the Oyster Creek nuclear plant, just a few miles from the coast, shut down as a precaution as Irene closed in. And Boston's transit authority said all bus, subway and commuter rail service were suspended Sunday.

Pennsylvania Gov. Tom Corbett warned that the state will not necessarily be out of danger once the storm has passed.

"The rivers may not crest until Tuesday or Wednesday. This isn't just a 24-hour event," he said.

The deaths blamed on Irene included two children, an 11-year-old boy in Virginia killed when a tree crashed through his roof and a North Carolina child who died in a crash at an intersection where traffic lights were out. Four other people were killed by falling trees or tree limbs — two in separate Virginia incidents, one in North Carolina and one in Maryland. A surfer and another beachgoer in Florida were killed in heavy waves.

As the storm's outer bands reached New York on Saturday night, two kayakers capsized and had to be rescued off Staten Island. They received summonses and a dressing-down from Bloomberg, who said they recklessly put rescuers' lives at risk.