Shelters opened and tens of thousands of people were ordered to evacuate coastal areas as cities and towns across the north- eastern United States took refuge against the onslaught of Hurricane Sandy.

The superstorm yesterday headed up the eastern seaboard on a collision course with two other weather systems.

New York City announced its subways, buses and trains would stop running, and its schools, attended by 1.1 million students, would be closed today.

Mayor Michael Bloomberg also ordered the evacuation of part of lower Manhattan and other low-lying neighbourhoods.

"If you don't evacuate, you are not only endangering your life, you are also endangering the lives of the first responders who are going in to rescue you," he said. "This is a dangerous storm."

Tens of thousands of people along the coast in Delaware, New Jersey, Connecticut and other threatened areas were also under orders to leave because of the danger of as much as 1ft of rain, punishing winds of 80mph and a potentially deadly tidal surge of 4ft to 8ft.

Sandy was headed north from the Caribbean, where it left nearly 60 dead. It is due to come ashore late tonight or early tomorrow, most likely in New Jersey, colliding with a wintry storm moving in from the west and cold air streaming down from the Arctic.