Superstorm Sandy shuts down northeastern US, threatens havoc

Millions of Americans in the country's heavily populated East Coast barricaded themselves in to brace up for a strengthened Hurricane Sandy that threatens catastrophe of a lifetime with forecasters warning that it will slam cities from New York to Washington.

Authorities declared a state of emergency from North Carolina to Connecticut as the superstorm made its way up the Atlantic on a collision course with two other weather systems, that could turn it into one of the most deadly storms to hit the US.

According to the National Hurricane Center's advisory, the storm's maximum sustained winds have maintained a speed of 85 miles per hour. The monster storm is about 310 miles southeast of New York and continues to speed up.

Warning that the megastorm could make landfall by later today or tomorrow morning, the forecasters said it could wreak havoc over 1,300 kms of eastern coastline to the Great Lakes.

The superstorm Sandy has plunged the final week of electioneering into chaos, with President Barack Obama and his Republican rival Mitt Romney cancelling and rescheduling their rallies in critical battleground states.

Dramatic rescue efforts were under way in Oak Orchard, Delaware, a community along the Indian River Bay and a part of the state that was under a mandatory evacuation. Officials across the Eastern Seaboard had implored residents to obey evacuation orders, emphasising that local authorities could be put in danger if they tried to save them.

New Jersey Governor Chris Christie put it most bluntly: "Don't be stupid. Get out!"

Still, some didn't leave. Delaware Governor Jack Markell said the National Guard and local fire and police officials were rescuing people in his state early this morning.

About 50 million people, from Virginia to Massachusetts, are expected to feel the effects of Sandy.

"It could be bad," said US Coast Guard Rear Admiral Steven Rattior, "or it could be devastation."