NEW YORK >> New York City transit officials say they’ve finished an unprecedented shutdown of the nation’s biggest system of subways, buses and commuter rails ahead of Hurricane Irene.

The Metropolitan Transportation Authority said Saturday night it had secured all its equipment and sent employees home. Mayor Michael Bloomberg says the edge of the hurricane has reached the city.

It’s unclear when the system will run again. The MTA says even if damage is minimal, restoring service "will be a lengthy process." And flooding, mudslides, fallen trees and downed power lines could dramatically complicate the work.

City subways alone carry about 5 million passengers on an average weekday.

In Manhattan,siidewalks, streets and bridges were nearly empty. Businesses were closed. Subway riders raced to catch the last trains. More 370,000 people in flood-prone areas were told to get out ahead of the storm, the first time such an evacuation order was issued for the city.

At the Seventh Avenue station in Brooklyn’s Park Slope section, more than a dozen people waited for one of the final subway runs.

"What I’m hoping is that they will run trains for the next hour or two to pick up the stragglers," said Kate Sandberg, who was headed to visit a friend.

It was the first time the city has shut down the entire subway system because of a natural disaster. Final subway and bus runs started at noon, and it would take about eight hours before the entire transit system was shuttered, city officials said.

Randall Moore of Brooklyn said he was turned around and boarded the wrong train while going to Queens from Harlem. He hoped he could still get back to his destination.

"The real problem once I get there is how I get back to 125th Street," he said. "I’m really hoping someone will give me a ride."

At the foot of the Brooklyn Bridge, stragglers scurried down the steps of the 4 and 5 lines to Brooklyn. Randy Callo barreled down two flights of steps and just made one of the final trains.

"This makes my day!" he said as the doors closed.

Salvatore Laudadio missed that train, and was sweating it out for one more ride to Brooklyn. He has been on a mass-transit odyssey on several buses and subway transfers.

"I got kind of a late start so I’ve been a little worried but I think this will all work out," he said, holding his bags.

Then the train rolled up and he got on.

The transit system won’t reopen until at least Monday, after pumps remove water from flooded subway stations. Even on a dry day, 13 million to 15 million gallons of water are removed from the tunnels deep underground. The Long Island Rail Road and other tracks were also being stopped.

The city’s public transit system carries about 5 million passengers on an average weekday and officials didn’t immediately report any problems during the final hours of the evacuation.

The last time the system was seriously hobbled was an August 2007 rainstorm that disabled or delayed every one of the city’s subway lines. It was also shut down after the 9/11 attacks and during a 2005 strike.

In Brooklyn’s Coney Island earlier, as rain started falling, Mayor Michael Bloomberg urged residents who needed to leave to get out right away.

The city does not have enough resources to evacuate the majority of the 370,000 affected residents.

"Staying behind is dangerous, staying behind is foolish, and it’s against the law, and we urge everyone in the evacuation zones not to wait until gale-force winds," he said at a news conference. "The time to leave is right now."

If the storm brings serious flooding, power could be cut off to the city’s most vulnerable areas, including the southern tip of Manhattan and parts of the West Village, said Consolidated Edison spokesman Chris Olert.

"We’re not doing anything proactively," he said. "This would be based on flood conditions."

Flooding could cause severe damage to underground cables, transformers and other equipment if power was left on. A shutdown "allows us to do repairs more quickly and safely," he said.

Transit fares and tolls were waived in evacuated areas. Officials hoped most residents would stay with family and friends, and nearly 100 shelters, with a capacity of 71,000 people, were opened.

On Wall Street, sandbags were placed around subway grates nearest the East River, which is expected to surge as the hurricane nears New York.

Bloomberg warned those who decided to stay that elevators in public housing apartments would be shut down, and other high-rises also quit working so people don’t get trapped if the power does go out.

Residents were urged to stay indoors once the weather started to get worse.

At 17 Battery Place, a 36-floor luxury rental building, Daryl Edelman and his wife, Regina, were leaving — suitcase packed and their small white dog, Bitsy Bananas, tucked into a case.

"What the mayor did — shutting down the transportation system — is more dangerous than the storm," said Daryl Edelman, a comic book writer. "People could be left stranded — especially the elderly."

Bloomberg said he hoped the evacuation wasn’t necessary, but officials needed to be cautious with what is considered a dangerous storm.

"You can’t prepare for the best case. You have to prepare for the worst case," he said.

Bloomberg weathered criticism after a Dec. 26 storm dumped nearly two feet of snow that seemed to catch officials by surprise. Subway trains, buses and ambulances got stuck in the snow, some for hours, and streets were impassable for days. Bloomberg ultimately called it an "inadequate and unacceptable" response.

Taxis in New York City were to switch from metered fares to zone fares, meaning riders would be charged by which part of the city they were being driven to, rather than how far they were being taken.

About 4,500 taxis were on the streets of Manhattan, which was just below an average day.

The five main New York City-area airports also closed at noon Saturday to arriving domestic and international flights. Three of them, Kennedy, LaGuardia and Newark Liberty, are among the nation’s busiest.

Irene made landfall in North Carolina on Saturday, and was expected to roll up the Interstate 95 corridor reaching New York on Sunday. A hurricane warning was issued for the city Friday afternoon, the first since Gloria in 1985.

"Heed the warnings," Bloomberg urged, his shirt soaking as the rain fell. "It isn’t cute to say ‘I’m tougher than any storm.’ I hope this is not necessary, but it’s certainly prudent."

About 1.6 million people live in Manhattan, and about 6.8 million live in the city’s other four boroughs.

In the past 200 years, New York has seen only a few significant hurricanes. In September 1821, a hurricane raised tides by 13 feet in an hour and flooded the southernmost tip of Manhattan in an area that now includes Wall Street and the World Trade Center memorial. In 1938, a storm dubbed the Long Island Express came ashore about 75 miles east of the city on neighboring Long Island and then hit New England, killing 700 people and leaving 63,000 homeless.

And in 1944, Midtown was flooded, where Times Square, Broadway theaters and the Empire State Building are located.

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Associated Press writers David B. Caruso, Tom Hays, Verena Dobnik, Jonathan M. Katz, Larry Neumeister, Emily Fredrix and Jennifer Peltz in New York and Michael Virtanen in Albany, N.Y., contributed to this report.