The extent of Hurricane Irene's destruction became clearer on Monday as the northeastern US states of New York and Vermont battled record flooding and the death toll climbed above 30. Major cities including New York took unprecedented evacuation measures and were largely spared the full wrath of Irene, which was downgraded on Sunday to a tropical storm as it drenched a vast stretch of the east coast. But the storm, whose death-strewn trail of carnage began a week ago in the Caribbean, refused to go out with a whimper, ravaging virtually the entire state of Vermont before crossing into Canada. "We're going to be digging out for a long time. Irene really whacked us hard," Governor Peter Shumlin told Vermont Public Radio. At the White House, President Barack Obama voiced concern about the flooding in Vermont and other states in the New England region. "It's going to take time to recover from a storm of this magnitude," he said. The top US disaster official, Craig Fugate, said around five million people remained without electricity, many further south in states like Virginia, and that it would take "some time to get all of the power back up." Vermont, a mountainous state criss-crossed by numerous streams and rivers, saw floods in virtually all major towns, including the capital Montpelier, where water levels began to recede Monday morning. "We are in uncharted territory," said Joe Kraus of the Central Vermont Public Service. "In many places, we can't even get to the damage." Dramatic television pictures from upstate New York and Vermont showed dangerous flash floods sweeping through residential areas and vast stretches of cascading water out in the country where rivers had burst their banks. While sun returned to most of the eastern United States, conditions were still risky. National Weather Service expert David Vallee said that key rivers such as the Connecticut were not likely to crest until Wednesday. Vallee described Irene as "a very well-behaved New England breed of hurricane," but said that conditions before the storm, including recent heavy rains, had made the ground wet and prone to flooding. A 21-year-old woman was presumed dead in Vermont after she joined her boyfriend in watching the rising waters of the Deerfield River on Sunday and was swept away. Officials and local media reported at least 33 deaths across 10 states, with six deaths each in New York state and North Carolina, where Irene made landfall Saturday with winds upwards of 85 miles (140 kilometers) an hour. The youngest fatalities were a boy killed by a falling tree in his apartment in Newport News, a city on a coastal peninsula in Virginia, and a girl who died in North Carolina. Canada recorded its first probable fatality after a man was swept away in Yamaska, northeast of Montreal, when two cars plunged into a chasm created when a road washed out, Quebec police said. The hurricane earlier last week killed at least five people in the Caribbean -- two each in the Dominican Republic and Haiti and one in the US territory of Puerto Rico. But the hurricane was not as severe as some people had prepared for. Wall Street rallied Monday in part on relief of limited damage to the infrastructure of the world's largest economy. New York's subway, which was closed Saturday in an unprecedented act of caution, reopened Monday morning, although suburban trains connecting suburbs in New Jersey, Connecticut and New York's Westchester County were suspended. National rail operator Amtrak also experienced major disruptions, with major lines shut down north of Philadelphia as crews cleared up debris and inspected the tracks. New York's airports reopened, but with delays. Eqecat Inc., a catastrophic risk management firm, estimated that damage to the eastern United States from the hurricane could reach up to $7 billion. Morgan Stanley nonetheless said that Irene would likely rank among the costliest 10 hurricanes in US history.