NAGS HEAD, N.C. -- Weaker but still menacing, Irene knocked out power and piers in North Carolina, clobbered Virginia with wind and churned up the coast yesterday to confront cities more accustomed to snowstorms than tropical storms.

With most of its transportation machinery shut down, the Eastern Seaboard spent the day nervously watching the storm's march across a swath of the nation inhabited by 65 million people.

The hurricane had an enormous wingspan -- 500 miles, its outer reaches stretching from the Carolinas to Cape Cod -- and packed wind gusts of 115 mph.

Almost 1 million homes and businesses were without power. While it was too early to assess the full threat, Irene was blamed for five deaths.

The deaths included two children: an 11-year-old boy in Virginia was killed when a tree crashed through his apartment building and a North Carolina child died in a crash at an intersection where traffic lights were out.

In addition, a North Carolina man was killed by a flying tree limb, a passenger died when a tree fell on a car in Virginia, and a surfer in Florida was killed in heavy waves.

The hurricane stirred up 7-foot waves, and forecasters warned of storm-surge danger on the coasts of Virginia and Delaware, along the Jersey Shore and in New York Harbor and Long Island Sound. In the Northeast, drenched by rain this summer, the ground is already saturated, raising the risk of flooding.

Irene made its official landfall just after first light near Cape Lookout, N.C., at the southern end of the Outer Banks, the ribbon of land that bows out into the Atlantic Ocean.

Shorefront hotels and houses were lashed with waves. Two piers were destroyed, and at least one hospital was forced to run on generator power.

By Saturday afternoon, the storm had weakened to sustained winds of 80 mph, down from 100 mph on Friday. That made it a Category 1, the least threatening on a 1-to-5 scale, and barely stronger than a tropical storm.

Shaped like a massive inverted comma, the storm had a thick northern flank that covered all of Delaware, almost all of Maryland and the eastern half of Virginia. A tornado touched down in Sussex County in Delaware, damaging at least 15 homes.

It was the first hurricane to make landfall in the continental United States since 2008, and came almost six years to the day after Katrina, a strong Category 3 hurricane, ravaged New Orleans.

Experts guessed that no other hurricane in American history had threatened as many people.

At least 2.3 million were under orders to move to somewhere safer, although it was unclear how many obeyed or, in some cases, how they could.

Defense Secretary Leon Panetta told 6,500 troops from all branches of the military to get ready to pitch in on relief work, and President Barack Obama visited the Federal Emergency Management Agency's command center in Washington and offered moral support.

"It's going to be a long 72 hours," he said, "and obviously a lot of families are going to be affected."

Airlines said 9,000 flights were canceled, including 3,000 yesterday. Airlines declined to say how many passengers would be affected.

The power losses were heavily concentrated in Virginia and North Carolina.

Get the latest news and more great videos at NewsdayTV Credit: Newsday

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Get the latest news and more great videos at NewsdayTV Credit: Newsday

Wild weather on LI ... Deported LI bagel store manager speaks out ... Top holiday movies to see ... Visiting one of LI's best pizzerias ... Get the latest news and more great videos at NewsdayTV

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