Hurricane Sandy killed at least 15 people and left millions of others without electricity on the East Coast of the United States, officials said Tuesday.

President Barack Obama signed disaster declarations overnight for the states of New York and New Jersey, which have been affected by storm surge and flooding.

More than 6.5 million people woke up Tuesday without electricity in 13 states battered by the storm, which continues to pound the Northeast with heavy rains and powerful winds.

New Jersey Gov. Chris Christie said 2.4 million customers had lost electric service in his state and the power was out in 95 percent of the city of Newark.

The storm surge and flooding damaged the grid in New York City, leaving nearly 2 million residents in the dark and forcing the financial markets to close for a second day, marking the first time the stock exchanges have been shuttered on consecutive days for weather-related reasons in more than a century.

Sandy has left millions of people without electricity from Maine to North Carolina, forcing airlines to cancel more than 13,000 flights out of over a dozen airports in the East, and paralyzing government operations.

The storm has also forced both Obama and his Republican rival, Mitt Romney, to cancel campaign events a week away from Election Day.

Sandy was moving through southern Pennsylvania at about 24 kph (15 mph) and was about 24 kilometers (15 miles) east of York and 145 kilometers (90 miles) west of Philadelphia, with maximum sustained winds of 105 kph (65 mph) at 0900 GMT, the National Weather Service said.

The storm made landfall Monday night near Atlantic City, New Jersey, packing maximum sustained winds of 125 kph (77 mph), sending a powerful storm surge into coastal areas in New Jersey and New York.

The rains from Sandy have caused flooding in Virginia, Maryland, Delaware and Pennsylvania.

At least seven people have died in New York and three others in New Jersey, with the total death toll in the United States now at 15, while one person was reported killed in Canada. EFE