Hurricane Sandy bore down on the Eastern Seaboard's largest cities Monday, forcing the shutdown of mass transit, schools and financial markets, sending coastal residents fleeing for higher
ground, and threatening a dangerous mix of high winds, soaking rain and a surging wall of water up to 11 feet tall.

Sandy stayed on a predicted path that could take it over Washington, Baltimore, Philadelphia and New York on its way to a collision course with two other weather systems, creating a
superstorm with the potential for havoc over 800 miles from the East Coast to the Great Lakes. About 2 to 3 feet of snow were even forecast for mountainous parts of West Virginia.

The tempest could endanger up to 50 million people for days.

Many workers planned to stay home Monday as subways, buses and trains shut down across the region under the threat of flooding that could inundate tracks and tunnels. Airports also closed, and authorities warned that the time for evacuation was running out or already past. Utilities brought in extra crews in anticipation of widespread power failures.

The centre of the storm was positioned to come ashore Monday night in New Jersey, meaning the worst of the surge could be in the northern part of that state and in New York City and on Long Island. Higher tides brought by a full moon compounded the threat to the metropolitan area of about 20 million people. ``This is the worst-case scenario,'' said Louis Uccellini,
environmental prediction chief for the National Oceanic and Atmospheric Administration.

As rain from the leading edges began to fall over the Northeast on Sunday, hundreds of thousands of people from Maryland to Connecticut were ordered to leave low-lying coastal areas, including 375,000 in lower Manattan and other parts of New York City, 50,000 in Delaware and 30,000 in Atlantic City, N.J., where the city's 12 casinos shut down for only the fourth time ever.

President Barack Obama declared emergencies in Massachusetts, Connecticut, Rhode Island, New York, New Jersey and Pennsylvania, authorizing federal relief work to begin well ahead of time. He promised the government would ``respond big and respond fast'' after the storm hits. ``My message to the governors as well as to the mayors is anything they need, we will be there, and we will cut through red tape,'' Obama said. ``We are not going to get bogged down with a lot of rules.''

Authorities warned that New York could get hit with a surge of seawater that could swamp parts of lower Manhattan, flood subway tunnels and cripple the network of electrical and communications lines that are vital to the nation's financial centre.

Major U.S. financial markets, including the New York Stock Exchange, Nasdaq and CME Group in Chicago, planned a rare shutdown Monday. The NYSE shut down on Sept. 27, 1985, for Hurricane Gloria. The United Nations also shut down and cancelled all meetings at its New York headquarters.

New York called off school Monday for the city's 1.1 million students and announced it would suspend all train, bus and subway service Sunday night. More than 5 million riders a day depend on the transit system.

Sandy, a Category 1 hurricane with sustained winds of 75 mph, was blamed for 65 deaths in the Caribbean before it began travelling northward, parallel to the Eastern Seaboard. As of 2 a.m. Monday, it was centred about 425 miles southeast of New York City, moving to the north at 14 mph, with hurricane-force winds extending an unusual 175 miles from its centre.

Gale-force winds blew overnight over coastal North Carolina, southeastern Virginia, the Delmarva Peninsula and coastal New Jersey.

Sandy was expected to hook inland Monday, colliding with a wintry storm moving in from the west and cold air streaming down from the Arctic, and then cut across into Pennsylvania and travel up through New York state.

Forecasters said the combination could bring close to a foot of rain in places, a potentially lethal storm surge of 4 to 11 feet across much of the region, and punishing winds that could cause
widespread power outages that last for days. The storm could also dump up to 2 feet of snow in Kentucky, North Carolina and West Virginia.

Airlines cancelled nearly 7,500 flights and Amtrak began suspending train service across the Northeast. New York, Philadelphia, Washington and Baltimore moved to shut down their
subways, buses and trains. Those cities shut down their schools, as did Boston. Non-essential government offices closed in the nation's capital. Pennsylvania's largest utilities brought in hundreds of line and tree-trimming crews in anticipation of several days of powerfailures or intentional shutdowns in areas with heavy flooding.