North Carolina's Dare County has ordered 30,000 residents and visitors to leave the Outer Banks' Hatteras Island as Hurricane Earl approaches.
Officials issued the order Wednesday evening for people in seven villages on the island. Only about 4,800 are permanent residents living from Rodanthe to Hatteras.
Hurricane Earl has strengthened back into a Category 4 storm and barreled toward the East Coast, packing winds of 135 mph.
A hurricane warning has been issued from the North Carolina coast to the Virginia state line, while a hurricane watch has been issued for the Delaware coast and Massachusetts.
The governors of North Carolina, Virginia and Maryland declared states of emergency, sea turtle nests on one beach were scooped up and moved to safety, and the crew of the Navy's USS Cole rushed to get home to Norfolk, Va., on Wednesday ahead of the bad weather.
The U.S. National Hurricane Center said Earl, just returned to a powerful Category 4 hurricane, could make landfall on the Carolinas as early as Thursday. The extended hurricane watch now includes popular resorts like Martha's Vineyard and Nantucket, the Miami-based center said.
Authorities gave mandatory evacuation orders for all visitors of two North Carolina vacation islands earlier Wednesday, warning that the storm's force will bring extremely high waves, heavy rains and dangerous riptides to much of the East Coast.
Dare County officials ordered the evacuation of Hatteras Island, part of North Carolina's Outer Banks, as officials said they are monitoring the storm before deciding whether to evacuate other parts of the county. A mandatory evacuation was also under way on neighboring Ocracoke Island in Hyde County.
The National Hurricane Center said that it does not expect Earl to dramatically weaken as it heads toward the Carolinas.
In Virginia Beach, where more than 20,000 long-distance runners, their families and friends are due to arrive this weekend for the Dodge Rock 'n' Roll Virginia Beach Half Marathon, organizers were keeping a close eye on the weather, but few participants had backed out.
"This is definitely on our radar, but at this time it looks like Sunday's half-marathon will take place as scheduled," said Dan Cruz.
Earl was still about 630 miles south-southeast of Cape Hatteras late Wednesday afternoon, with top sustained winds of 135 mph. The hurricane was moving to the northeast at about 17 mph, the National Hurricane Center said.
Bill Read, director of the center, said dry air to the west may prevent the storm from "re-intensifying," but said there is still no indication that it will lose strength as it heads toward the Northeast.
"I don't have anything that I'm aware of to cause it to radically weaken," Read said in a briefing with reporters. "The eye looks very well defined."
Read, however, said he is "highly confident" that the hurricane will make a northeast turn starting late on Thursday, sparing the East Coast from the worst of the storm.
President Obama on Wednesday said federal and local authorities are preparing for a "worst case" scenario in anticipation of Earl. Just days after commemorating the fifth year anniversary of Hurricane Katrina, Obama said in a statement that officials will "do everything needed to protect the residents and communities along the East Coast."
Obama, who was briefed earlier by Federal Emergency Management Agency administrator Craig Fugate, said such precautions include "encouraging residents and visitors in potentially affected areas to follow all evacuation orders issued by local and state officials."
Hurricane warnings -- issued 36 hours in advance -- mean that hurricane conditions are expected somewhere along a specified coastal region, according to the National Oceanic and Atmospheric Administration. Hurricane watches, by contrast, are issued 48 hours in advance to prepare residents for possible tropical-storm-force winds in particular coastal areas.
Tourists on Ocracoke Island boarded ferries to the mainland early Wednesday, and more evacuations could be on the way as Earl threatened to sideswipe the East Coast.
Hyde County spokeswoman Jamie Tunnell said about 30 cars, including trucks pulling campers, were lined up to board ferries that would begin leaving Ocracoke Island on the state's Outer Banks for the 2 1/2-hour trip to shore.
"Ferries are the only way off unless you have a private plane or boat," Tunnell said.
The evacuation orders are called mandatory, but Julia Jarema, spokeswoman for the state Division of Emergency Management, said it doesn't mean people will be forced from their homes. Local law enforcement officials may do something such as going door-to-door and asking people who stay behind to provide information about their next of kin.
Emergency officials said they hoped Ocracoke's 800 or so year-round residents would heed the call to leave. But Carol Paul said she and husband Tom would stay put if the current forecasts hold. Only a direct hit from a stronger storm would drive them from the island where they've lived for seven years, running an antiques store.
"There's never been a death on Ocracoke from a hurricane, so we feel pretty comfortable," Carol Paul, 57, said as tourists departed on ferries and her husband, also a construction contractor, worked to board up the windows of clients and friends' homes. "Everything here is made pretty much with hurricanes in mind."
More evacuations along the Eastern Seaboard could follow, depending on the path taken by the storm, which was downgraded to a Category 3 hurricane early Wednesday as it whipped across the Caribbean with winds of 125 mph (200 kph). The storm was upgraded back to a Category 4 storm late Wednesday afternoon, when wind speeds reached 135 mph.
Earl was expected to remain over the open ocean before turning north and running parallel to the East Coast, bringing high winds and heavy rain to North Carolina's Outer Banks by late Thursday or early Friday. From there, forecasters said, it could curve away from the coast somewhat as it makes its way north, perhaps hitting Massachusetts' Cape Cod and the Maine shoreline on Friday night and Saturday.
Forecasters cautioned that it was still too early to tell how close Earl might come to land. But not since Hurricane Bob in 1991 has such a powerful storm had such a large swath of the East Coast in its sights, said Dennis Feltgen, spokesman for the National Hurricane Center.
"A slight shift of that track to the west is going to impact a great deal of real estate with potential hurricane-force winds," Feltgen said.
Virginia's governor on Wednesday planned to declare an emergency, a preliminary step needed to muster emergency personnel should Earl hit the state. And Maryland Gov. Martin O'Malley is advising travelers not to drive to or from Ocean City during the height of stormy weather from Earl.
Emergency officials as far north as Maine, meanwhile, are checking their equipment and urging people to have disaster plans and supplies ready.
George Baker, head of the Cape Emergency Management Readiness in Massachusetts, told MyFoxBoston.com on Tuesday that authorities won't deploy emergency teams until 48 hours in advance of the storm. Baker spoke the same day strong currents swept two men out to sea within hours of each other in Gloucester, killing one of them.
Officials in New Jersey and Long Island are also bracing for dangerous rip currents at the start of the Labor Day weekend. Authorities in Seaside Park, N.J., for example, are reportedly expecting waves anywhere from 6 to 10 feet.
Behind Earl and Tropical Storm Fiona in the Atlantic, the seventh tropical storm of the season formed. Forecasters said Wednesday that Gaston is the fourth tropical storm to form in the last 11 days.
Gaston's top sustained winds are about 40 mph.
The Associated Press contributed to this report