MOREHEAD CITY, N.C. (AP) — Whipping up trouble before ever reaching land, Hurricane Irene zeroed in Friday for a catastrophic run up the Eastern Seaboard. More than 2 million people were told to move to safer places, and New York City ordered its entire network of subways shut down for the first time because of a natural disaster.

As the storm's outermost bands of wind and rain began to lash the Outer Banks of North Carolina, authorities in points farther north begged people to get out of harm's way. The hurricane lost some strength but still packed 100 mph winds, and officials in the Northeast, not used to tropical weather, feared it could wreak devastation.

"Don't wait. Don't delay," said President Barack Obama, who decided to cut short his summer vacation by a day and return to Washington. "I cannot stress this highly enough: If you are in the projected path of this hurricane, you have to take precautions now."

Senior hurricane specialist Richard Pasch of the National Hurricane Center said there were signs that the hurricane may have weakened slightly, but strong winds continued to extend 100 miles from its center.

The moment Saturday when the eye of the hurricane crosses land "is not as important as just being in that big swath," Pasch said. "And unfortunately, it's a big target."

Hurricane warnings were issued from North Carolina to New York, and watches were posted farther north, on the islands of Nantucket and Martha's Vineyard off Massachusetts. Evacuation orders covered at least 2.3 million people, including 1 million in New Jersey, 315,000 in Maryland, 300,000 in North Carolina, 200,000 in Virginia and 100,000 in Delaware.

"This is probably the largest number of people that have been threatened by a single hurricane in the United States," said Jay Baker, a geography professor at Florida State University.

New York City ordered more than 300,000 people who live in flood-prone areas to leave, including Battery Park City at the southern tip of Manhattan, Coney Island and the beachfront Rockaways. But it was not clear how many would do it, how they would get out or where they would go. Most New Yorkers don't have a car.

On top of that, the city said it would shut down the subways and buses at noon Saturday, only a few hours after the first rain is expected to fall. The transit system carries about 5 million people on an average weekday, fewer on weekends. It has been shut down several times before, including during a transit workers' strike in 2005 and after the Sept. 11 attacks a decade ago, but never for weather.

Mayor Michael Bloomberg said there was little authorities could do to force people to leave.

"We do not have the manpower to go door-to-door and drag people out of their homes," he said. "Nobody's going to get fined. Nobody's going to go to jail. But if you don't follow this, people may die."

Shelters were opening Friday afternoon, and the city was placed under its first hurricane warning since 1985.

Transit systems in New Jersey and Philadelphia also announced plans to shut down, and Washington declared a state of emergency. Boisterous New Jersey Gov. Chris Christie demanded people "get the hell off the beach" in Asbury Park and said: "You're done. Do not waste any more time working on your tan."

Hundreds of thousands of airline passengers were grounded for the weekend. JetBlue Airways said it was scrubbing about 880 flights between Saturday and Monday, most to and from hub airports in New York and Boston. Other airlines said they were waiting to be more certain about Irene's path before announcing more cancellations.

Thousands of people were already without power. In Charleston, S.C., several people had to be rescued after a tree fell on their car.

Defying the orders, hardy holdouts in North Carolina put plywood on windows, gathered last-minute supplies and tied down boats. More than half the people who live on two remote islands, Hatteras and Ocracoke, had ignored orders to leave, and as time to change their minds ran short, officials ordered dozens of body bags. The last ferry from Ocracoke left at 4 p.m. Friday.

"I anticipate we're going to have people floating on the streets, and I don't want to leave them lying there," said Richard Marlin, fire chief for one of the seven villages on Hatteras. "The Coast Guard will either be pulling people off their roofs like in Katrina or we'll be scraping them out of their yards."

Officially, Irene was expected to make landfall Saturday near Morehead City, on the southern end of the Outer Banks, the barrier island chain. But long before the eye crossed the coastline, the blustery winds and intermittent rains were already raking the coast. By Friday evening 50 mph winds were measured at Wrightsville Beach, N.C.

Some took to shelters for protection.

Susan Kinchen, her daughter and 5-month-old granddaughter came to West Carteret High School with about 50 others. She said they didn't feel safe in their trailer, and the Louisiana native was reminded of how her old trailer lost its roof to Hurricane Katrina, almost six years ago to the day, on Aug. 29, 2005.

"We live in a trailer with her," said Kinchen, referring to the infant. "I'm not taking any chances."

Hurricane center meteorologist David Zelinsky said earlier Friday that he expected the storm to arrive as a Category 2 or 3 hurricane. Later in the day, other forecasts showed it would strike most of the coast as a Category 1. The scale runs from 1, barely stronger than a tropical storm, to a monstrous 5. On Friday night, Irene was a Category 2.

The hurricane center said Irene could weaken into a tropical storm before reaching New England, but that even below hurricane strength it would be powerful and potentially destructive.

Regardless of how fierce the storm is when it makes landfall, the coast of North Carolina was expected to get winds of more than 100 mph and waves perhaps as high as 11 feet, Zelinsky said.

"This is a really large hurricane and it is dangerous," he said. "Whether it is a Category 2 or 3 at landfall, the effects are still going to be strong. I would encourage people to take it seriously."

Officer Edward Mann was driving down the narrow streets of Nags Head looking for cars in driveways, a telltale sign of people planning to ride out the storm against all advice.

Bucky Domanski, 71, was working in his garage when Mann walked in. He told the officer he planned to stay. Mann handed Domanski a piece of paper with details about the county's evacuation order. It warned that hurricane force winds would flood the roads and there might not be power or water until well after the storm.

"You understand we can't help you during the storm," Mann said.

"I understand," Domanski replied.

After the Outer Banks, the next target for Irene was the Hampton Roads region of southeast Virginia, a jagged network of inlets and rivers that floods easily. Emergency officials have said the region is more threatened by storm surge, the high waves that accompany a storm, than wind. Gas stations there were low on fuel Friday, and grocery stores scrambled to keep water and bread on the shelves.

In Delaware, Gov. Jack Markell ordered an evacuation of coastal areas.

"We could be open tonight for business, but there's a very fine line between doing the right thing and putting our staff at risk," said Alex Heidenberger, owner of Mango Mike's restaurant in Bethany Beach, who expects to lose $40,000 to $50,000 in business. "It's not so much we're worried about the storm coming tonight, but we want to give them a chance to get out of town and get their affairs in order."

Officials at Walter Reed Army Medical Center in Washington said they were speeding the transfer of their last remaining patients to the National Naval Medical Center in Bethesda, Md. The transfer had been planned for Sunday.

In Baltimore's Fells Point neighborhood, one of the city's oldest waterfront neighborhoods, people filled sandbags and placed them at the entrances to buildings. A few miles away at the Port of Baltimore, vehicles and cranes continued to unload huge cargo ships that were rushing to offload and get away from the storm.

In New York, the Mets postponed games scheduled for Saturday and Sunday with the visiting Atlanta Braves. The Jets and Giants moved their preseason NFL game up to 2 p.m. Saturday from 7 p.m., but then postponed it until Monday.

And in Atlantic City, N.J., all 11 casinos announced plans to shut down Friday, only the third time that has happened in the 33-year history of legalized gambling in that state.

"I like gambling, but you don't play with this," Pearson Callender said as he waited for a Greyhound bus out of town. "People are saying this is an act of God. I just need to get home to be with my family."