NEW YORK — Millions of people from Maine to the Carolinas awoke Tuesday without power, and an eerily quiet New York City was all but closed off by car, train and air as superstorm Sandy steamed inland, still delivering punishing wind and rain.

The full extent of the damage in New Jersey, where the storm roared ashore Monday night with hurricane force, was unclear. Police and fire officials, some with their own departments flooded, fanned out to rescue hundreds.

“We are in the midst of urban search and rescue. Our teams are moving as fast as they can,” Gov. Chris Christie said. “The devastation on the Jersey Shore is some of the worst we’ve ever seen. The cost of the storm is incalculable at this point.”

The death toll from Sandy in the U.S. climbed to 18, including six in New York, four in Pennsylvania and three in New Jersey, with most of the victims killed by falling trees. Sandy also killed 69 people in the Caribbean before making its way up the Eastern Seaboard.

At least 7.4 million people across the East were without electricity. Airlines canceled more than 12,000 flights.

Lower Manhattan, the financial center of the U.S., was among the hardest-hit areas after the storm sent a nearly 14-foot surge of seawater, a record, coursing over its seawalls and highways and into low-lying streets.

Water cascaded into the gaping, unfinished construction pit at the World Trade Center, and the New York Stock Exchange was closed for a second day, the first time that has happened because of weather in more than a century.

A huge fire destroyed as many as 100 houses in a flooded beachfront neighborhood in Queens on Tuesday, forcing firefighters to undertake daring rescues. Three people were injured.

A downtown hospital, New York University’s Tisch, evacuated 200 patients after its backup generator failed. About 20 babies from the neonatal intensive care unit were carried down staircases and on battery-powered respirators.

And a construction crane that collapsed in the high winds on Monday still dangled precariously 74 floors above the streets of midtown Manhattan.

With water standing in two major commuter tunnels and seven subway tunnels under the East River, there was no indication of when the nation’s largest transit system would be rolling again. It shut down Sunday night ahead of the storm.

Joseph Lhota, chairman of the regional Metropolitan Transportation Authority, said the damage was the worst in the 108-year history of the New York subway.

Millions of more fortunate New Yorkers surveyed damage as dawn broke, their city brought to an extraordinary standstill.

“Oh, Jesus. Oh, no,” Faye Schwartz said she looked over damage in neighborhood in Brooklyn, where cars were scattered like leaves.

Besides the subway and the stock exchange, most major tunnels and bridges in New York were closed, as were schools, Broadway theaters and the metropolitan area’s three main airports, LaGuardia, Kennedy and Newark.

“This will be one for the record books,” said John Miksad, senior vice president for electric operations at Consolidated Edison, which had more than 670,000 customers without power in and around New York City.

In New Jersey, a huge swell of water swept over the small town of Moonachie, near the Hackensack River, and authorities struggled to rescue about 800 people, some of them living in a trailer park. Police and fire officials used boats to try to reach the stranded.

Jersey City was closed to cars because traffic lights were out, and Hoboken, just over the Hudson River from Manhattan, dealt with major flooding. In Atlantic City, most of the world-famous boardwalk was intact, but pieces washed away Monday night.

Remnants of the hurricane were forecast to head across Pennsylvania before taking another sharp turn into western New York by Wednesday morning. Although weakening as it goes, the storm will continue to bring heavy rain and flooding, said Daniel Brown of the National Hurricane Center in Miami.

As Hurricane Sandy closed in on the Northeast, it converged with a cold-weather system that turned it into a monstrous hybrid of rain, high wind — and even snow in West Virginia and other mountainous areas inland.

Just before it made landfall at 8 p.m. near Atlantic City, N.J., forecasters stripped Sandy of hurricane status, but the distinction was purely technical, based on its shape and internal temperature.

While the hurricane’s 80 mph winds registered as only a Category 1 on a scale of five, it packed the lowest barometric pressure on record in the Northeast, giving it terrific energy to push water inland.

President Barack Obama declared a major disaster in the city and Long Island. The storm brought the presidential campaign to a halt with a week to go before Election Day.

In New York, the construction crane atop a 1,000-foot, $1.5 billion luxury high-rise in midtown Manhattan dangled for a second day while authorities tried to figure out how to secure it. Thousands were ordered to leave nearby buildings as a precaution, including 900 guests at the ultramodern Le Parker Meridien hotel.

Alice Goldberg, 15, a tourist from Paris, was watching television in the hotel — whose slogan is “Uptown, Not Uptight” — when a voice came over the loudspeaker and told everyone to leave.

“They said to take only what we needed, and leave the rest, because we’ll come back in two or three days,” she said as she and hundreds of others gathered in the luggage-strewn marble lobby. “I hope so.”

An explosion Monday night at a substation for Consolidated Edison, the main utility service New York City, knocked out power to about 310,000 customers in Manhattan.

“It sounded like the Fourth of July,” Stephen Weisbrot said from his 10th-floor apartment.

One of the units at Indian Point, a nuclear power plant north of New York City, was shut down Monday night because of electrical grid problems, said Entergy Corp., which operates the plant. The company said there was no risk to the public.

And officials declared an “unusual event” at the Oyster Creek nuclear power plant in Lacey Township, N.J., the nation’s oldest, when waters surged to 6 feet above sea level during the evening.

Within two hours, the situation at the reactor — which was offline for regular maintenance — was upgraded to an alert, the second-lowest in a four-tiered warning system.

In Baltimore, fire officials said four unoccupied rowhouses collapsed in the storm, sending debris into the street but causing no injuries. A blizzard in western Maryland caused a pileup of tractor-trailers that blocked part of Interstate 68 on slippery Big Savage Mountain.

“It’s like a long-tailed cat in a room full of rocking chairs up here,” said Bill Wiltson, a Maryland State Police dispatcher.  

Hundreds of miles from the storm’s center, gusts topping 60 mph prompted officials to close the port of Portland, Maine, and scared away several cruise ships.