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President Bush laid a wreath on the wind-swept field where Flight 93 crashed five years ago, and privately greeted family members in a cold drizzle as they marked the loss of the 40 passengers and crew.

The president and first lady stopped for a moment of silence and bowed their heads during a prayer and the singing of "Amazing Grace." Bells tolled in memory of the victims, and the president shook hands with each family member.

Complete coverage of the anniversary of 9/11 is available in FOXNews.com's special Sept. 11 Center

United Airlines Flight 93 had been headed to San Francisco from Newark, N.J., when the hijackers took over, apparently planning to crash the plane into the White House or the Capitol. Conversations from the flight's final minutes indicate the passengers had some idea of what was happening and, on the words "Let's roll," stormed the cockpit in an effort to wrest control shortly before the crash.

"We stand here today with pride because of heroism," said Hamilton Peterson, whose father and stepmother died when the plane went down.

A 10-foot-tall chain-link fence stands near the site as a temporary memorial, festooned with American flags, firefighters' helmets and drawings by children.

"It just shows people don't forget," said Larry Antonio of Gilbertsville, who came to the site with his wife Barbara to observe the anniversary of the terrorist attacks.

The first rescue crews to arrive at the western Pennsylvania field five years earlier found only a smoking crater, singed trees and silence.

"My first thought was, where's the plane crash?" said state police Lt. Patrick Madigan. "All there was was a hole in the ground and a smoking debris pile."

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Since the crash, a group of volunteers known now as the Flight 93 ambassadors point visitors to the crash site and describe what happened aboard the plane on Sept. 11, 2001. Some months they guide more than 25,000 visitors.

Organizers hope to raise $30 million in private funding to build a permanent memorial on a 1,700-acre site in Shanksville; the total cost is estimated to be $58 million. Congress has passed the Flight 93 Memorial Act, which established a new national park to honor the victims of the hijacked plane.

At the ceremony, Rendell announced that the state would be signing a commitment letter to give $10 million to the memorial effort, and that it had acquired 300 acres around the crash site that will be managed as a public wildlife area.

"This action will forever preserve the entrance to the memorial in an undeveloped and natural setting," Rendell said.

On that terrible day in 2001, it didn't take first responders long to realize there would be no survivors. Combing the site, all they could find at first were small pieces of aircraft — and bits of a United Airlines in-flight magazine.

"It was a pretty scary time," says a former assistant fire chief, Rick King, whose truck was the first to arrive. "I just remember driving down the road, wondering what we were about to see."

Searchers recovered only about 8 percent of the potential human remains but were able to identify everyone from the fragments they did find, said Somerset County Coroner Wallace Miller.

"Most of the material was vaporized," he says.

Complete coverage of the anniversary of 9/11 is available in FOXNews.com's special Sept. 11 Center