SHANKSVILLE, Pa. — For Mike Pence, it was personal.

As the vice president on Monday addressed those who lost loved ones on the 9/11 plane that crashed into rural Pennsylvania instead of hitting its intended target in Washington, D.C., he got choked up.

“I will always believe that I, and many others in our nation’s capital, were able to go home that day to hug our families because of the courage and selflessness of the heroes of Flight 93,” Pence said as his wife, Karen, sat behind him.

He called the efforts by the 40 crew members and passengers who revolted against the terrorist hijackers “a debt I don’t think I’ll ever be able to repay.”

Pence spoke at a memorial service at the crash site on a day that was as sunny and clear as it was 16 years ago.

Vice President Pence speaks to visitors at the Flight 93 National Memorial on Sept. 11, 2017, in Shanksville, Pa. (Photo: Jeff Swensen, Getty Images)

Pence, in 2001, hadn’t finished his first year as a House member from Indiana the morning planes hit the World Trade Center and the Pentagon.

The Capitol building and nearby House and Senate office buildings were hemorrhaging lawmakers and aides, Pence remembers, as people ran in every direction, not knowing if they would be the next to be attacked.

Pence ended up with congressional leaders in the office of the Capitol police chief. The room became silent as the chief told those gathered that there was a plane inbound for the Capitol. It was 12 minutes away.

“It was the longest 12 minutes of my life,” Pence said. “But it turned to 13 minutes, then 14, and then we were informed that the plane had gone done in a field in Pennsylvania.”

Because Flight 93 had been delayed in leaving Newark, N.J., passengers were able to learn about other attacks from airfones they used after being forced by their hijackers to sit in the back of the plane. They developed a plan to try to stop the terrorists, and charged the cockpit.

“They were ordinary people,” Pence said. “But on that day, they became extraordinary.”

Rather than risking the crew regaining control of the plane, the terrorists crashed it into the ground, killing all onboard.

At the time the plane was supposed to have hit the Capitol, Pence was standing with hundreds of others near the building’s east front.

“They might well have saved my own life that day,” Pence said.

His trip Monday wasn’t the first time Pence had come in thanks. On one of the family’s drives back to Washington from Indiana in the year after the attacks, the Pences brought their three children to the site. On that visit, there was only a makeshift memorial and a wooden cross in the field.

Returning as vice president to an extensive national memorial site and fields of wildflowers, Pence had a broader message than his personal gratitude.

On behalf of President Trump, Pence promised that the U.S. military will “hunt down and destroy” ISIS “at their source.” And, noting that the 9/11 attacks were orchestrated from Afghanistan, Pence said America will “remain engaged in Afghanistan until we eliminate the terrorist threat to our homeland and our people once and for all.”

“We will drive the cancer of terrorism from the face of the earth,” he said.

Most of the morning, however, was a solemn tribute to Flight 93.

David Dosch, a United Airlines pilot who was the best friend of Captain Jason Dahl, the flight’s pilot, helped ring the bells which chimed for each of the 40 crew members and passengers.

Vice President Pence and his wife, Karen, tour the Flight 93 National Memorial on Sept. 11, 2017, in Shanksville, Pa. (Photo: Jeff Swensen, Getty Images)

The National Park Service broke ground Sunday for a permanent “Tower of Voices” of 40 wind chimes. The 93-foot tower will be the final phase of major construction of the memorial’s original design.

Pence said the notes will form a perfect harmony, “just as, in their final moments, the men and women of Flight 93 worked together to defend freedom.”

After his remarks, Pence toured the visitor center with Stephen Clark, superintendent of the National Parks of Western Pennsylvania.

One of the first exhibits included items from the World Trade Center (a mangled fork and knife from “Windows on the World”), the Pentagon (a family photo from a Navy officer’s office) and the Capitol (a replica of the “Freedom” statue that sits atop the dome, which Pence said he gazed at after hearing 16 years ago that a plane was headed their way).

Pence nodded along as Clark described the exhibit showing the flight path of Flight 93 including a video simulation of the last minutes of flight.

“You can see what the heroes were trying to do to take back control of the airplane,” Clark said.

A National Park Service ranger presents a wreath to Vice President Pence and Interior Secretary Ryan Zinke at the Flight 93 National Memorial on Sept. 11, 2017, in Shanksville, Pa. (Photo: Jeff Swensen, Getty Images)

As he looked at a wall of those heroes’ photographs, Pence put his arm around his wife.

Outside, the couple held hands as they walked out to the Flight Path Overlook. The overlook looks down on the crash site, which is marked with a boulder.

“So well done,” Karen Pence said as they walked back to the visitor center.

Down near the crash site, friends and family members of the passengers and crew gathered at a wall inscribed with the names of the fallen. Flowers, origami cranes, and a superman doll were among the items left on the ground below their names.

Dosch, who lives in Washington state, said he tries to come every September not just as a tribute to his friend, but to share the experience with others who lost loved ones on the flight.

“It’s always good to see their faces,” he said, after posing for photos with a Japanese woman who comes every year to honor her son, an exchange student, killed on the flight.

Joined by the siblings of the flight’s crew members, the Pences bowed their heads in silence in front of a wreath of white flowers placed before the wall of names.

Then Pence led a procession of family members onto the now-grassy land where the plane went down, a final moment away from the television cameras where he could say his thanks in private.