Ambulances carrying patients evacuated from NYU Langone Medical Center leave the facility heading for other hospitals, Monday night in New York, October, 29, 2012. In the midst of an outage caused by Hurricane Sandy, the hospital's backup power generator failed prompting the evacuation of most patients. (Chang W. Lee/The New York Times)
Ambulances carrying patients evacuated from NYU Langone Medical Center leave the facility heading for other hospitals, Monday night in New York, October, 29, 2012. In the midst of an outage caused by Hurricane Sandy, the hospital's backup power generator failed prompting the evacuation of most patients. (Chang W. Lee/The New York Times)
Reporting on the storm was contributed by Peter Applebome, Charles V. Bagli, Joseph Berger, Nina Bernstein, Cara Buckley, Russ Buettner, David W. Chen, Annie Correal, Sam Dolnick, Christopher Drew, David W. Dunlap, Ann Farmer, Lisa W. Foderaro, Joseph Goldstein, David M. Halbfinger, Elizabeth A. Harris, Winnie Hu, Jon Hurdle, Thomas Kaplan, Corey Kilgannon, John Leland, Randy Leonard, Patrick McGeehan, Jad Mouawad, Colin Moynihan, Sarah Maslin Nir, Sharon Otterman, William K. Rashbaum, Ray Rivera, Liz Robbins, Wendy Ruderman, Nate Schweber, Michael Schwirtz, Mosi Secret, Kirk Semple, Joe Sharkey, Brian Stelter, Kate Taylor, Julie Turkewitz, Matthew L. Wald, Michael Wilson, Michael Winerip, Vivian Yee and Kate Zernike.

As Hurricane Sandy churned inland as a downgraded storm, residents up and down the battered mid-Atlantic region woke Tuesday to lingering waters, darkened homes and the daunting task of cleaning up from once-in-a-generation storm surges and their devastating effects.

Power remained out for roughly 6 million people, including a large swath of Manhattan in New York. Early risers stepped out into debris-littered streets that remained mostly deserted as residents waited for dawn to shed light on the extent of the damage. Bridges remained closed, and seven subway tunnels under the East River remained flooded.

The storm was the most destructive in the 108-year history of New York City's subway system, said Joseph J. Lhota, the chairman of the Metropolitan Transportation Authority, in an early morning statement.

"We are assessing the extent of the damage and beginning the process of recovery," he said, but did not provide a timetable for restoring transit service to a paralyzed city.

At least 16 deaths - including seven in the New York region - were tied to the storm, which toppled trees and sparked fires in several areas, The Associated Press reported.

Nine hours after making landfall at 8 p.m. on Monday, the storm - already reclassified as a post-tropical cyclone - weakened as it passed west across southern Pennsylvania, though it still packed maximum sustained winds of 65 mph, the National Hurricane Center said. It was expected to turn north and head for Canada late on Tuesday.

The storm had picked up speed as it roared over the Atlantic Ocean on Monday, grinding life to a halt for millions of people in more than a half-dozen states, with extensive evacuations that turned shorefront neighborhoods into ghost towns.

Hurricane force winds extended up to 175 miles from the center of the storm; tropical storm force winds spread out 485 miles from the center. Forecasters said tropical storm force winds could stretch all the way north to Canada and all the way west to the Great Lakes. Heavy snow was expected in some states.

Businesses, schools and roads were closed, and more than 13,000 airline flights were canceled. Even the Erie Canal was shut down.

Subways were shut down from Boston to Washington, as were Amtrak and the commuter rail lines. Flights were canceled at airports across the East Coast, including the three major airports in the New York City area. And late Monday night, Mayor Michael R. Bloomberg said cabs had been instructed to get off New York City roads.

The wind-driven rain lashed sea walls and protective barriers in places like Atlantic City, where the Boardwalk was damaged as water forced its way inland. Foam was spitting, and the sand gave in to the waves along the beach at Sandy Hook, N.J., at the entrance to New York Harbor. Water was thigh-high on the streets in Sea Bright, N.J., a three mile sand-sliver of a town where the ocean joined the Shrewsbury River.

"It's the worst I've seen," said David Arnold, watching the storm from his home in Long Branch, N.J. "The ocean is in the road, there are trees down everywhere. I've never seen it this bad."

In Breezy Point in New York, nearly 200 firefighters were still battling a blaze on Tuesday morning that destroyed at least 50 tightly-packed homes in the beach community. A Fire Department spokesman said the area was "probably the most flooded part of the city, so there are all sorts of complications."

The surging water also caused extensive complications at NYU Langone Medical Center when a backup power system failed on Monday night, forcing the evacuation of patients to other facilities.

Backup power also failed at Coney Island Hospital in southern Brooklyn, though critical patients had been evacuated in advance of the storm.

In New York, Gov. Andrew M. Cuomo's office said late Monday night that at least three deaths in the state were caused by falling trees from the storm. About 7 p.m., a tree fell on a house in Queens, killing a 30-year-old man, the city police said. About the same time, two boys, ages 11 and 13, were killed in North Salem, in Westchester County, when a tree fell on the house they were in, according to the state police.

In Morris County, N.J., a man and a woman were killed when a tree fell on their car Monday evening, AP reported.

Earlier, a construction crane atop one of the tallest buildings in New York City came loose and dangled 80 stories over West 57th Street, across the street from Carnegie Hall.

As the storm lashed the city, waves topped the sea wall in the financial district in Manhattan, sending cars floating down streets. West Street, along the western edge of Lower Manhattan, looked like a river. The Brooklyn-Battery Tunnel flooded "from end to end," the transportation authority said, hours after Cuomo had ordered it closed to traffic. Officials said water also seeped into seven subway tunnels under the East River.

"In 108 years, our employees have never faced a challenge like the one that confronts us now," Lhota, the transit authority chairman, said.

A replica of the HMS Bounty, a tall ship built for the 1962 movie "Mutiny on the Bounty" starring Marlon Brando and used in the recent "Pirates of the Caribbean" series, sank off the North Carolina coast. The Coast Guard said the 180-foot three-masted ship went down near the Outer Banks after being battered by 18-foot-high seas and thrashed by 40 mph winds. The body of one crew member, Claudene Christian, 42, was recovered. Another crew member remained missing.

Delaware banned cars and trucks from state roadways other than "essential personnel."

"The most important thing right now is for people to use common sense," Gov. Jack A. Markell said. "We didn't want people out on the road going to work and not being able to get home again."

By early Monday evening, the storm had knocked out power to hundreds of thousands of homes, stores and office buildings.

Consolidated Edison said that as of 1:30 a.m. Tuesday, 634,000 customers in New York City and Westchester were without power. Con Edison, fearing damage to its electrical equipment, shut down power pre-emptively in sections of Lower Manhattan on Monday evening, and then, at 8:30 p.m., an unplanned failure, probably caused by flooding in substations, knocked out power to most of Manhattan below Midtown, about 250,000 customers. Later, an explosion at a Con Edison substation knocked out power to another 250,000 customers.

In New Jersey, more than 2 million customers were without power as of 1:30 a.m. Tuesday, and in Connecticut the total reached nearly 500,000 customers.

Forecasters attributed the power of the storm to a convergence of weather systems. Alex Sosnowski, a senior meteorologist with AccuWeather, said potentially damaging winds would continue on Tuesday from Illinois to the Carolinas - and as far north as Maine - as the storm barreled toward the eastern Great Lakes.

The storm headed toward land with weather that was episodic: a strong gust of wind one minute, then mist. More wind. Thin sheets of rain dancing down the street. Then, for a moment, nothing. The sky lightened. Then another blast of rain. Then more wind.

In some places, caravans of power-company trucks traveled largely empty roads; Public Service Electric and Gas said that 600 line workers and 526 tree workers had arrived from across the country, but could not start the repairs and cleanup until the wind had subsided, perhaps not until Wednesday.

They will see a landscape that, in many places, was remade by the storm. In Montauk, at the end of Long Island, a 50-seat restaurant broke in half. Half of the building floated away and broke into pieces on the beach.

The 110-foot-tall lighthouse at Montauk Point - the oldest in the state, opened in 1796 - shuddered in the storm despite walls that are six feet thick at the base. The lighthouse keeper, Marge Winski, said she had never felt anything like that in 26 years on the job.

"I went up in the tower and it was vibrating, it was shaking," she said. "I got out of it real quick. I've been here through hurricanes, and nor'easters, but nothing this bad."