Updated 11:57 pm ET
MOREHEAD CITY, N.C. - 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 the nation's biggest subway system 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 was still packing 100 mph winds late Friday, 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,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 90 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 1 million people in New Jersey, 315,000 in Maryland, 300,000 in North Carolina 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.
Late Friday, aviation officials said they would close the five main New York City-area airports to arriving domestic and international flights beginning at noon on Saturday. Many departures also were canceled.
The airports are John F. Kennedy International, Newark Liberty International, LaGuardia, Stewart International and Teterboro.
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.
Some of the first New Yorkers to evacuate were the elderly patients from a Coney Island nursing home. Howard Small, a longtime administrator, hadn't seen a day like this in 39 years.
"This has never been enacted," he told CBS News. "This has never been used in practice. It's just been tested in theory."
In New York area sports, the football Giants and Jets originally moved their preseason game up from Saturday night to the afternoon, but decided on Friday to postpone it until Monday night.
The games between baseball's Atlanta Braves and New York Mets scheduled for Saturday and Sunday were postponed, rescheduled as a single-admission doubleheader on Sept. 8 beginning at 4:10 p.m.
Transit systems in New Jersey and Philadelphia also announced plans to shut down, and Washington declared a state of emergency.
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 was set to leave 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."
Carol Dillon, the 82-year-old owner of Outer Banks Motel in Buxton, North Carolina, said she's not leaving -- in fact she never leaves during hurricanes. Her motel guests were gone.
"I'm doing everything I can to protect what property I have," she told CBS News. "If it happens it happens. I've learned to take life as it comes and try not to cry about it."
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.
National 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 afternoon, Irene was a Category 2.
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."