Teenage students from Greater Johnstown School District were clambering about the rope course set in the rural beauty of Camp Harmony that morning, and teacher Lugene Shaver felt good about it.

They were kids with extra challenges in life who benefited from bonding and thrills at the faith-centered camp, set in the breathtaking topography of southwestern Pennsylvania. On high ground away from the woods, you could see forested rolling humps that stretched into the distance, sometimes appearing gauzy bluish-green in haze.

It was about 10 a.m. when Shaver heard a loud and strange-sounding plane pass rapidly overhead.

"There was an odd noise to it," she recalled. "It sputtered. It seemed to turn off and on."

And then it was gone, off to the south.

Lugene Shaver saw jet exhaust lingering in a strange pattern. It didn't look like a normal, straight jet contrail.

What had been going on in that plane?

Americans fighting terrorism

It was, the world later learned, Americans fighting back on the morning of Sept. 11, 2001, against terrorists who had commandeered the Boeing 757 jetliner. Their likely intent was to crash it into the U.S. Capitol.

All 40 passengers and crew members died in the attempt to retake the plane. They were among 2,977 Americans who died that day in multiple terrorist attacks.

On Friday, it was clear that the selflessness and sacrifice of the 40 passengers and crew of United Airlines Flight 93 are alive and well in American hearts.

Had they not summoned the courage to do what they did, U.S. Secretary of the Interior Doug Burgum said at the Flight 93 National Memorial in southwestern Pennsylvania, the world "would be very different today."

He spoke during a moving 90-minute memorial ceremony in the afternoon at the National Park Service-operated site, attended by hundreds. The day was mostly sunny with scattered gray-bottomed cumulus clouds floating over the field where the plane had crashed.

Off to the right of the speakers' tent was the long, marble "Wall of Names" etched with the names of the 40, and to the left a chorus of dozens of school children.

Twenty-five years earlier, Flight 93 had left Newark International Airport at 8:42 a.m., bound for San Francisco. During the next hour, three other terrorist-commandeered jetliners were crashed into both towers of the World Trade Center in Manhattan and the Pentagon in Washington, D.C.

On Flight 93, hijackers attacked the cockpit crew at 9:28 a.m., and in a short time some crew members and passengers were placing calls to people on the ground, becoming more and more aware that a coordinated attack on the country was underway.

Seen from the ground

Radiators, headlights, hoods, tail lights. Pretty much any auto part could be found in the vast spread of junked vehicles at Stoystown Auto Wreckers about two miles south of Camp Harmony.

Employee Terry Butler was out among the wrecks around 10 a.m. that morning, looking for parts. Butler heard something and turned around. He saw a plane do something very strange right there in front of him, above the hills, flying very low and going very fast.

"It went up a little bit. I am not quite sure how high," Butler recalled. Then it veered in another direction, at an angle, where he could see both wings.

Then, he heard the crash, felt the ground shake, and saw black smoke go up like a mushroom cloud.

In a diner at nearby Reels Corner, with its jukebox, booths, and stools, Pat Gisbrecht was working as a waitress.

Abruptly, the building shook.

Gisbrecht, now 67, recalled, "My boss came out and said, 'Did you feel that?'"

In Somerset, roughly eight miles from where the smoke cloud appeared, Fleetwood Folding Trailers had a factory where Rodger Ashbrook worked on the assembly line.

Ashbrook recalled a lot of employees being summoned that morning into the big "rain room" that had sprinklers on the ceiling. It was the place where they tested the waterproofing of the campers.

There, they learned that America was under attack. "They sent us all home," said Ashbrook.

A bit later, he stopped for a few groceries at a service station. There, people were looking out toward an open area where smoke was rising above the horizon.

Staring evil in the face

Aboard Flight 93, passengers had taken a vote and made a decision to try and take back the plane. They began their attack at 9:57 a.m. The 9/11 Commission Report said the assault was "sustained" and, when the terrorists apparently judged they were about to be overwhelmed, they crashed the plane while traveling at 580 miles per hour.

It struck a former strip mine just north of Shanksville about 10:03 a.m. that morning.

The spirit of the passengers and crew was on the mind of every speaker at the memorial on Friday.

"They organized, they mobilized, an they summoned the courage to stare evil in the face and fight back," Gov. Josh Shapiro said.

Gordon Felt, who lost a brother on Flight 93 and has long been a spokesperson for family members, said the founders of the U.S. staked everything on the concept that ordinary people could defend the nation. The Flight 93 passengers and crew, he said, proved it.

He urged today's citizens, in terms of courage, to "live as they lived in their final minutes."

Impossible to comprehend

It's been 25 years and Becky Sarver is 76 years old.

Still, she gets emotional about it.

That morning, she was the kitchen sink when something rattled the dishes and the knickknacks on the shelves. She thought maybe a local mine was doing blasting.

A short time later, out driving, she passed many ambulances, fire trucks, and police cars, all headed for the area just south of her home. She and her husband of 26 years, pipefitter Wayne Sarver, later got calls from many people seeking to find out if they and their home were okay.

Sarver was working at a small market in the area about a week later when some family members of those who had died in the crash came in. One of them told Sarver her son had been one of the passengers on the phone from the plane.

Sarver never forgot the conversation with the grieving mother. This week, she cried as she recalled it.

She said, "I couldn't comprehend what they went through. It just tears you up."