New York and the east coast of America is bracing itself for the impact of Hurricane Irene.
New Yorkers living in low-lying areas have been warned to get out before the storm hits the city of 8.4m people.
The city's mass transit system might have to be shut down tomorrow, making it difficult for residents to leave if they wait, Mayor Michael Bloomberg said.
Hurricane Irene, raging up from the Caribbean toward the US east coast, is expected to hit New York on Sunday with winds of up to 153kph.
Bloomberg made it clear people in coastal areas such as Battery Park City on Manhattan's southern tip, Coney Island and the Rockaways should not linger until he issues an evacuation order because that could endanger emergency workers.
Police Commissioner Raymond Kelly promised an increased police presence in evacuated neighbourhoods to deter looting.
New York's mass transit system is the largest in the United States, serving 8m people a day.
The subways might have to be shut because surging sea water could damage equipment.
Irene has already destroyed hundreds of homes on small Bahamian islands as it makes its way toward the US eastern coast.
There were no immediate reports of deaths in the Bahamas from the Category 3 hurricane, but some small settlements reported up to 90pc of their homes damaged.
Irene was only the third storm since 1866 to cross the entire length of the island chain.
The US National Hurricane Centre in Miami, Florida, said it was expected to dump from six to 12 inches (15 to 30cm) of rain on the islands.
Irene's core moved north of the Bahamas chain last night, and the government lifted hurricane warnings for all but Grand Bahama and the Abaco islands.
The storm headed toward the US, where it sent thousands of vacationers fleeing and threatened up to 65m people from the Carolinas to New England. It would be the strongest to strike the East Coast in seven years.
The former chief of the National Hurricane Centre called it one of his three worst possible situations.
"One of my greatest nightmares was having a major hurricane go up the whole northeast coast," Max Mayfield, the centre's retired director, said, adding the damage will probably climb into billions of dollars,"This is going to have an impact on the United States economy," he said.
"It's not going to be a Katrina, but it's serious," said MIT meteorology professor Kerry Emanuel. "People have to take it seriously."