More than 1 million people across a dozen states were under orders to evacuate as the massive storm continued to plow westward.
NEW YORK: Superstorm Sandy, one of the fiercest storms ever to hit the United States, has left at least 16 people dead and over six million people in darkness as it continues to batter the nation's eastern seaboard with unprecedented ferocity.
As the damage from the 'Frankenstorm' continues to grow, President Obama declared a state of emergency in New York City, AFP reported.
Though downgraded to a "post-tropical" superstorm Monday evening by the National Hurricane Centre, Sandy unleashed powerful winds and torrential rains from North Carolina to Maine and knocked out power across 11 states and the national capital.
Over 700,000 homes and businesses were without power in New York City and Westchester county, out of a total of 3 million Con Edison customers.
More than 1 million people across a dozen states were under orders to evacuate as the massive system continued to plow westward.
One disaster forecasting company predicted economic losses could ultimately reach $20 billion, only half insured.
In New York City, emergency backup power failed and 10 feet of water flooded the basement of NYU Langone Medical Center, forcing the evacuation of 260 patients. Nurses manually pumped air to the lungs of those on respirators, reported CNN.
Lower Manhattan's Battery Park recorded a 12.75 ft tide, breaking a record set in 1960 with Hurricane Donna. The city halted service on its bus and train lines, closing schools and ordering about 400,000 people out of their homes in low-lying areas of Manhattan and elsewhere.
As New York's skyscrapers were being battered, a crane snapped and dangled from the side of a luxury high-rise under construction Far above West 57th Street.
The iconic Grand Central Station in New York bore an eerily deserted look and the subway shut down for only the second time in its history.
Hurricane-force winds stretched from Cape Cod to the Virginia coast as Sandy swept ashore, with its storm surge setting new high-water records for lower Manhattan and swamping beachfronts on both sides of Long Island Sound.
Mass transit shut down across the densely populated Northeast, landmarks stood empty and schools and government offices were closed. The National Grid, which provides power to millions of customers, said 60 million people could be affected before it's over.
"I've been down here for about 16 years, and it's shocking what I'm looking at now. It's unbelievable," Montgomery Dahm, owner of the Tun Tavern in Atlantic City, which stayed open as Sandy neared the Jersey Shore, was quoted as saying.
By Monday afternoon, 23 states were under a warning or advisory for wind related to Sandy. Thousands of flights had been cancelled, and hundreds of roads were flooded.
With the storm expected to linger longer than most, the federal workforce and public employees in the national capital, Maryland and Virginia were told to stay home for a second day Tuesday.
No flights were expected Tuesday in or out of the region's three airports, where scores of travellers were stranded Monday after airlines halted service throughout the Northeast. (Agencies)