NEW YORK — The normally bustling streets emptied out and the rumble of the subways came to a stop.
New York buttoned up Saturday against Hurricane Irene, which threatened to paralyze Wall Street and give the big city its worst thrashing from a storm since at least the 1980s.
City officials cautioned that if Irene stayed on track, it could bring gusts of 85 mph overnight that could shatter skyscraper windows. They said there was an outside chance that a storm surge in Lower Manhattan could send seawater streaming into the maze of underground vaults that hold the city's cables and pipes, knocking out power to thousands and crippling the nation's financial capital.
Mayor Michael Bloomberg ordered the first mandatory evacuation ever in New York. More than 370,000 people were told to be out by 5 p.m. from low-lying areas on the fringes of the city, mostly in Lower Manhattan, Brooklyn and Queens.
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Many New Yorkers seemed to take it in stride, staying off the streets and hunkering down. Some planned hurricane get-togethers and hot tub parties.
"We already have the wine and beer, and now we're getting the vodka," said Martin Murphy, a video artist who was shopping at a liquor store near Central Park with his girlfriend.
"If it lasts, we have dozens of movies ready, and we'll play charades and we're going to make cards that say, 'We survived Irene,'" he said.
All subway service was suspended because of the threat of flooding in the tunnels — the first time the nation's biggest transit system has shut down because of a natural disaster. Sandbags and tarps were placed on or around subway grates.
"Heed the warnings," Bloomberg said, his shirt getting soaked as the rain fell in Coney Island. "It isn't cute to say, 'I'm tougher than any storm.' ... I hope this is not necessary, but it's certainly prudent."
People arrived in a trickle at a shelter set up at a high school in the Park Slope section of Brooklyn. Some carried garbage bags filled with clothing; others pushed carts loaded with their belongings.
They were evacuated from a public housing project in Brooklyn's Red Hook section. Tenants said management got them to leave by telling them the water and power would be shut off at 5 p.m.
"For us, it's him," said Victor Valderrama, pointing to his 3-year-old son. "I didn't want to take a chance with my son."
In Times Square, shops boarded up windows, put sandbags outside entrances and the street performer known as the Naked Cowboy, who stands at the Crossroads of the World wearing only underwear and a guitar, had a life vest on.
Construction came to a standstill across the city, and workers at the World Trade Center site dismantled a crane and secured equipment. The mayor said there would be no effect on the opening of the Sept. 11 memorial on the 10th anniversary of the terrorist attacks.
Con Edison brought in hundreds of extra utility workers from around the country. While the foot of Manhattan is protected by a seawall and a network of pumps, Con Ed vice president John Mucci said the utility stood ready to turn off the power to about 6,500 customers there in the event of severe flooding.
Mucci said it could take up to three days to restore the power if the cables became drenched with saltwater, which can be particularly damaging.
The New York Stock Exchange has backup generators and can run on its own, a spokesman said.
Con Ed also shut down about 10 miles of steam pipes underneath the city to prevent explosions if they came in contact with cold water. The shutdown affected 50 commercial and residential customers around the city who use the pipes for heat, hot water and air conditioning.
While Bloomberg strongly cautioned against staying put, he also said no one was going door-to-door to force residents out. And many apparently chose not to go.
The city opened more than 90 evacuation shelters with room for about 70,000 people. But by early evening, only about 5,500 had checked in, officials said.
Subway trains began grinding to a halt at noon.
The transit system won't reopen until at least Monday, after pumps remove water from flooded stations. The subways routinely flood during even ordinary storms and have to be pumped out.