KITTY HAWK, North Carolina -- Tens of thousands of people fled their homes on the U.S. East Coast on Tuesday and dozens of navy vessels were ordered out to sea to avoid a collision with Hurricane Isabel.

Isabel eased slightly but was still packing winds of 170 kilometers (105 miles) an hour as it headed for an expected landfall early Thursday, according to the U.S. National Hurricane Center.

Forecasters said Isabel would pack its first punch in North Carolina and then sweep up the seaboard toward Washington. Nearly 50 million people live in the path Isabel is expected to take.

North Carolina and Virginia issued states of emergency and evacuations orders were made for an area covering about 110,000 people, mainly on the small Outer Bank islands off North Carolina and beach resorts on the coast.

About 23,000 people in North Carolina's Dare county were affected by the evacuation order.

In summer the Dare population swells to 150,000 but Frank Pierce, a state public safety spokesman, said there were few tourists in the county now. North Carolina Governor Mike Easley urged people to "stock up on needed supplies such as gasoline and water, and tune to news broadcasts to hear the latest updates from emergency management personnel."

Thousands of home and store owners from South Carolina to Virginia and Maryland rushed to board up windows and buy emergency food, batteries and first aid kits. Several hardware stores reported shortages, AFP reported.

Todd Liston, 34, screwed sheets of plywood onto the metal frame of the windows of the offices of his seaside pool company in Kitty Hawk. This hurricane "looks pretty serious, more than usual," said Liston. "We're pretty prepared here, more than further inland."

Liston said that he has had to board up the windows several times because of hurricanes, including in 1999 for Hurricane Floyd. "Most people kept their plywood from last time," he said.

U.S. warships began steaming out of the giant U.S. naval base at Norfolk, Virginia, to get out of Isabela's path.

Up to 40 submarines and warships, including the carrier USS Ronald Reagan, headed to sea to ride out the hurricane, the U.S. Navy said.

An Atlantic Fleet spokesman said the ships were to leave port every 10 to 15 minutes, and about 110 F/A-18 and F-14 fighters based at nearby Oceana Naval Station were also sent to other bases beyond the reach of the storm. Air Force One, President George W. Bush's airplane based at Andrews Air Force Base near Washington, was also ordered to fly inland, officials said.

The air force was to empty six East Coast bases, sending squadrons of fighters, refueling aircraft, transport planes and helicopters to bases to the U.S. Midwest, said a spokeswoman.

A hurricane watch was in effect from Little River inlet in South Carolina, to Chincoteague, in northeast Virginia, meaning it could hit in about 36 hours, according to the Florida-based Hurricane Center.

Isabel's center was located about 917 kilometers (570 miles) southeast of North Carolina's Cape Hatteras. The hurricane was heading in a northwestern direction at a speed of nearly 13 kilometers (eight miles) per hour, according to the center. "While some further weakening is possible," the weather service said in a statement, "conditions could become favorable for restrengthening prior to landfall."

Isabel is currently a Category two hurricane on the Saffir-Simpson scale, which goes to five. Over the weekend Isabel was a Category Five, packing winds of up to 260 kilometers (160 miles) per hour.

"The public must continue to take this storm seriously," said Tim Schott, a spokesman for the National Weather Service.