An emergency was declared in eight affected states on the eastern coast even as the hurricane monitors said windspeeds had diminished as the storm moved north.
US President Barack Obama himself was on top of the things personally, monitoring the preparedness for hurricane Irene, the first to hit the Big Apple in decades.
America's economic nerve centre New York virtually shut down as New Yorkers prepared for the onslaught of violent winds and flooding.
However, the hurricane weakened to a tropical storm as it moved through New Jersey and New York but fear of flooding in many areas still loomed large as river water began inundating some of Manhattan's streets.
Mayor Michael Bloomberg said time was already up to evacuate and those still in the city must take precautions.
"At this point, if you haven't evacuated, our suggestion is you stay where you are... Nature is a lot stronger than the rest of us," he said.
The National Hurricane Center said windspeeds had diminished as the storm moved north capping off at 75 miles an hour, slightly above the minimum needed to considered a Category I hurricane. However, weather experts said the relentless rain still made it very dangerous.
"Even though they are saying that the storm is quote-on- quote weakening, hurricane winds are hurricane winds," John Searing, the deputy commissioner of the Suffolk County Department of Fire, Rescue and Emergency Services said just before daybreak as he prepared to deal with the damage.
"Whether they say its 80 miles or 75 miles an hour, what's the physical difference in that?" he was quoted as saying by New York Times.
Obama, who has declared State of Emergency in eight States, held two conference calls with his top national team.
Cities in several States had declared curfew and police were not allowing people to come out on the streets.
Emergency shelter homes were opened in cities across the eastern Coast so that people affected by the hurricane can take shelter.
As almost all airports were shut down due to precautionary measures, thousands of flights have been cancelled.
The flightaware.com website, which tracks airport arrivals and departures, estimated that 8,337 flights would be cancelled during the weekend, mainly US domestic trips. It warned that the figure would rise.
Air India flights from New Delhi and Mumbai have also been cancelled today from both the airports in New York and New Jersey, an airlines official said.
All the Hindu temples and gurdwaras in the region, which are normally thronged by Indian Americans on Sundays have been closed as a precautionary measure.
Metro services were suspended in several cities including New York, Washington and Boston.
Reports said at least 12 had died in North Carolina, Virginia and Florida.
Half of the deaths were in North Carolina, where Irene made landfall early yesterday morning.
The toll rose from eight overnight with new fatalities including a man hit by a falling tree in North Carolina, a woman in Maryland hit by a falling chimney, and a man killed by a storm-related electrical fire in Connecticut.
The breakdown of fatalities was: six in North Carolina, three in Virginia, and one each in Connecticut, Florida in Maryland.
The youngest fatalities were a boy killed by a falling tree in his apartment in Newport News, a city on a coastal peninsula in Virginia, and a girl who died in North Carolina.
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