NEW YORK - Much of New York City remained shut down Tuesday in the aftermath of superstorm Sandy, a rare, powerful storm that killed at least 30 people in seven states and knocked out power for an estimated 7.4 million customers.

The storm killed 69 people in the Caribbean before hitting the United States, where it left many coastal communities under water.

New York City Mayor Michael Bloomberg told reporters Tuesday that at least 10 people were killed in the region, and he expected the death toll to climb. Falling trees caused many of the fatalities. Bloomberg also reported drownings and the death of someone who stepped in a puddle that had a live wire in it.

"I think people don't understand just how strong nature is," Bloomberg said.

The Federal Emergency Management Agency listed more than a dozen states as "active disaster areas." On Tuesday morning, President Barack Obama declared "major disaster" areas in New York and New Jersey. Consolidated Edison Co. of New York was forced to cut power to thousands of customers in lower Manhattan and Brooklyn in in an attempt to minimize storm damage.

"This will be one for the record books," ConEd senior vice president John Miksad said in an overnight conference call with reporters. "This will be the largest storm-related outage in our history."

Some ConEd customers should expect to be without power for more than a week, the company said Tuesday morning. Metropolitan Transit

Authority Chairman Joseph Lhota said in a statement Tuesday morning that New York's 108-year-old transit system "has never faced a disaster as devastating as what we experienced last night." Seven subway tunnels under the East River flooded, and the Hugh L. Carey Tunnel that connects Brooklyn to Manhattan "flooded from end to end."

Bloomberg said there was "no firm timeline" for reopening the subway system but estimated it could be "a good four or five days."

National Guard vehicles and helicopters were called into the state to help with ongoing search and rescue operations in New Jersey, where 2.4 million people were without power on Tuesday morning, according to Gov. Chris Christie. More than a dozen water facilities in the state were damaged, posing a threat to drinking water, Christie said. The governor called the damage devastating "beyond anything I ever thought I'd see," and said the cost of the storm is "incalculable."

Officials told New Jersey residents to be ready for the worst on Tuesday, when they could begin to assess the damage from flooding, downed trees and power lines, according to The Trentonian. Public Service Electric & Gas CEO Ralph Izzo called the damage unprecedented.

"We've never had a direct hit of a hurricane like this," Izzo said. "Certainly never have seen the storm surge that we saw."

People near Philadelphia area were cautioned to stay off the roadways, where fallen trees were wrapped with downed power lines, according to The Times Herald in Norristown. In Connecticut, the Coast Guard on Tuesday resumed its search for a 40-year-old man who disappeared in heavy surf around 8 p.m. Monday, according to a report in The New Haven Register.
Connecticut residents who were forced to evacuate their homes later in the storm had difficulty finding hotels, some of which wouldn't even answer their phones, the newspaper reported.

Nationally, the Associated Press put the death toll at 33.

In New York, Bloomberg said he expected the period of flooding was over but that a long period of repair was just beginning. "Conditions are still dangerous," he said. "I just can't stress that enough."