Super-storm Sandy has engulfed the eastern United States, flooding much of New York City, battering several states with heavy winds, torrential rain and claiming lives.
The massive storm stretched over hundreds of kilometres and paralysed several major cities as it brought coastal flooding and hurricane-force winds to the densely-populated east coast and blizzards to the mountainous interior. Up to 16 people were reported to have died in the US by early on Tuesday.
Sandy first made landfall on the coast of New Jersey near Atlantic City about 8pm (local time) on Monday with winds of about 129km/h, paralysing transport networks, causing hundreds of thousands of people to evacuate and closing financial markets.
Seawater coursed between skyscrapers of New York's financial district in lower Manhattan, flooding subways and road tunnels and shorting out the power grid, plunging an estimated six million households into darkness, AFP reports.
Sandy sent a record storm surge of 4.15 metres into lower Manhattan, flooding seven major subway tunnels used by hundreds of thousands of daily commuters and swamping cars in the financial district.
"The New York City subway system is 108 years old, but it has never faced a disaster as devastating as what we experienced last night," city transport director Joseph Lhota said.
The National Hurricane Centre said wind speeds inside Sandy dropped as the storm became a post-tropical cyclone, but remained hurricane-force at 120km/h after it made landfall near Atlantic City. Much of the casino resort is under water, and 30,000 residents have been evacuated.
Further south, the sea surged over vast swaths of the eastern seaboard, turning coastal cities into ghost towns as the high winds grounded planes and shut down rail links, public transport and government offices.
Disaster estimating firm Eqecat forecast that Sandy would affect more than 60 million Americans - a fifth of the population - and cause up to $US20 billion in damage.
The New York Stock Exchange, the Nasdaq and the futures markets in Chicago were closed for Monday and Tuesday.
The storm has overshadowed the US election race, forcing a halt to campaigning a week before Americans are due to go to the polls on 6 November to choose between President Barack Obama and Republic challenger Mitt Romney.
Mr Obama urged Americans to heed local evacuation orders and signed emergency declarations to free up federal disaster funds for New York state, Massachusetts, Connecticut, Maryland, the District of Columbia, New Jersey, Pennsylvania, Rhode Island, Virginia and West Virginia.
Hurricane Sandy had killed 67 people as it tore through the Caribbean, and reports of more deaths began to arrive after the storm made landfall in the US.
Officials in New York, New Jersey, Pennsylvania, Maryland, West Virginia and North Carolina reported at least 16 dead in storm-related incidents, while in Toronto police said a Canadian woman was killed by flying debris.
A woman pulled from the water has died after the replica sailing ship Bounty sank off the North Carolina coast. The captain is still missing, presumed drowned, but 14 crew were rescued from life rafts.
Authorities warned the threat to life and property was "unprecedented" and ordered hundreds of thousands of residents in areas from New England to North Carolina to evacuate their homes and seek shelter.
Power plants affected
A nuclear power plant in New Jersey declared an alert as waters rose on Monday. The Oyster Creek power plant, just north of Atlantic City, was already on a scheduled outage as Sandy made landfall, and the industry regulator said there was no immediate danger.
Hours earlier, a power substation exploded in a burst of light as a massive blackout left much of Manhattan, and some 500,000 homes across New York City, in darkness, AFP reports.
Fire fighters used inflatable orange boats to rescue utility workers trapped for three hours by floodwaters inside a Con Edison power substation. The waters had begun to recede early on Tuesday, but the company said it could take a week to completely restore power.
The operator of two major New Jersey nuclear plants said they might have to be closed, threatening half the state's power supply.
Rare hybrid storm
Forecasters say Sandy is a rare, hybrid super storm created by an Arctic jet stream wrapping itself around a tropical storm.
A third storm is also involved - a system coming down from Canada could effectively hold Sandy in place, amplifying the inland flooding effects.
Sandy is forecast to collide with cold weather fronts from the west and north and coincides with a full moon, which is bringing higher tides.
The super-storm could linger over 12 states for 24 to 36 hours from Monday, bringing heavy rain and snow, the BBC reports.