NEW YORK -- With solemn ceremonies and prayers, moments of silence and the ringing of bells, the nation Sunday marked the 15th anniversary of the Sept. 11, 2001, terrorist attacks that killed 2,977 people.
Commemorations unfolded in New York and outside Washington, where hijackers piloted planes into the World Trade Center and Pentagon, and at a rural field in Pennsylvania, where a plane crashed after passengers fought back against their hijackers.
In New York, organizers estimated 8,000 people gathered Sunday at the lower Manhattan spot where the twin towers once stood. They listened to the nearly four-hour recitation of the names of those killed.
Both Hillary Clinton and Donald Trump attended the ceremony in lower Manhattan, but the Democratic nominee left after about an hour and a half. She felt overheated, according to a statement from campaign spokesman Nick Merrill.
Clinton appeared to stumble as she approached her vehicle and had to be helped. But she went to daughter Chelsea's apartment to rest, and is "feeling much better," Merrill said.
She emerged about two hours later, saying as she left, "It's a beautiful day in New York." Asked if she was feeling better, she replied: "Yes, thank you very much."
The New York ceremony started with a moment of silence at 8:46 a.m. EDT, coinciding with the time the first plane struck the north tower. Some bowed their heads while others held high photos of their loved ones.
Family members came to the stage in pairs to read the names and sometimes add a heartfelt message about the victims.
Joseph Quinn, who lost his brother, Jimmy, appealed to Americans to regain the sense of unity that welled up after the terror attacks.
"I know, in our current political environment, it may feel we're divided. Don't believe it," said Quinn, who added that he served in the military in Iraq after 9/11. "Engage with your community. ... Be the connection we all desperately need."
Jeremy D'Amadeo was 10 when his father, Vincent, was killed at the World Trade Center, and he spent many summers at a camp for children of 9/11 victims.
"This summer I had the privilege of working with kids who had their own tragic loss, kids of Sandy Hook," D'Amadeo said.
"These kids lifted me up and made me know that I wanted to give back as much as I can.
"Sometimes the bad things that happen in our lives put us on the paths we should be going, to help others as much as we can. P.S., Dad, I love you."
James Johnson was at ground zero for the first time since he last worked on the rescue and recovery efforts in early 2002, when he was a New York police officer.
The 9/11 museum and memorial plaza, three skyscrapers, and an architecturally audacious transit hub have been built on land that was a disaster zone when he last saw it.
"I've got mixed emotions, but I'm still kind of numb," said Johnson, now a police chief in Forest City, Pa. "I think everyone needs closure, and this is my time to have closure."
Cathy Cava, on the other hand, has attended all 15 anniversary ceremonies since she lost her sister Grace Susca Galante.
"I believe most of her spirit, or at least some of her spirit, is here," Cava said. "I have to think that way."
'Let's roll!' remembered
At the Flight 93 National Memorial in southwestern Pennsylvania, the ceremony included music, the reading of the names of the 40 victims who died there and the ringing of bells.
About 1,000 surviving family members, dignitaries and other visitors attended the annual service at the Flight 93 National Memorial in Shanksville. The site, about 60 miles southeast of Pittsburgh, is where the United Airlines flight crashed as passengers -- one calling out "let's roll!" -- staged a rebellion and stormed the cockpit to fight back against four hijackers.
For the first time, the Shanksville ceremony was held on the grounds outside the visitor center that opened last year rather than at the marble wall that runs along the crash site.
Investigators believe the hijackers meant to crash the plane into the Capitol, or possibly the White House, after the flight from Newark, N.J., to San Francisco was commandeered by the terrorists and steered toward Washington, D.C.
Interior Secretary Sally Jewell was the keynote speaker in Shanksville, and she spoke about the need to commemorate the crash site as a national park.
"Fifteen years ago today, the course of American history changed," Jewell said. "Certainly the men and women of Flight 93 had no idea they would be heroines and heroes that day."
Addressing the victims' families, Jewell said, "You have known the terrible pain of loss. None of us would want to trade places with you, but we honor your sacrifice."
Gordon Felt, the president of the Families of Flight 93, an advocacy group that helped push for and design the park, said just one aspect of the memorial remains to be completed, the Tower of Voices. The 93-foot-tall tower will contain 40 wind chimes and is scheduled for completion by 2018.
But Felt, whose brother Edward died in the crash, cautioned that the memorial park is about "so much more than the surrounding structures, our losses and the effects of Sept. 11 on our lives."
"Most of us today do not need marble walls, a tower of chimes or even a visitors' center to remind us of the sacrifices here 15 years ago," Felt said.
"These structures and design aspects are not for us. They are for those who have forgotten. They are for tomorrow's children."
The surviving families visited the visitor center privately following the ceremony, before it opened to the public.
The families then were to visit the memorial itself, a wall with the names of each victim engraved on individual panels that line the crash site. Some were expected to walk to the site itself along a path that is generally not open otherwise.
Jewell said it's clear that the visitor center is educating those too young to remember the attacks. She read from one entry by a 17-year-old visitor in the center's log book.
"You've all done a completely selfless act for the good of our nation," Jewell read from the teen's entry. "You'll be rewarded in heaven for your courageous deeds. God bless America. May you rest in peace."
Obama at Pentagon
At the ceremony at the Pentagon in Arlington, Va., an American flag hung from the roof of the building where American Airlines Flight 77 barreled into the limestone exterior.
It billowed in gusts of wind that moved streaks of clouds across the pale blue sky, occasionally blocking out the sun.
"As Americans, we do not give in to fear," President Barack Obama said at the Pentagon Memorial service as about 800 family and friends of those who died stood for 30 seconds of silence at 9:37 a.m. EDT, the same time of morning that a jetliner struck the building and killed 184 people.
"The most enduring memorial ... is ensuring the America we continue to be, that we stay true to ourselves, stay true to what is best in us, that we not let others divide us," Obama said.
Defense Secretary Ashton Carter and Joint Chiefs of Staff Chairman Joseph Dunford Jr. joined Obama in placing a wreath of white lilies in the memorial garden.
"There are a million places I'd rather be than at the Pentagon," said Devora Kirschner, 40, whose husband was working as a Naval intelligence officer when he died in the attack.
As she spoke, a jetliner flew past the building, taking off from Reagan National Airport nearby. "Especially with planes flying overhead," she said, standing next to her husband's bench. "It's unnerving."
Abraham Scott, 64, came to the Pentagon with his two daughters, two granddaughters and other relatives and friends.
His wife, Janice Marie Scott, was working as a budget officer at the Pentagon on the morning of the attack.
Scott has worked with other people who lost loved ones on 9/11 to push the federal government to adopt the recommendations of the 9/11 Commission.
He lobbied lawmakers to pass a law that would strip sovereign immunity from countries believed to support terrorism, opening up the ability for victims of terror attacks to sue countries that may have helped carry out an attack.
That bill, called the Justice Against Sponsors of Terrorism Act, was already approved by the Senate and was passed by the House on Friday. The bill will be sent to the White House for Obama's signature.
The president has been reluctant to support the bill, saying that other countries could adopt similar polices that would open the U.S. government up to a raft of new liabilities and lawsuits for its actions overseas.
The bill comes as the U.S. can't say for certain whether the country is safer from terrorist attacks.
"It's a mixed bag," Homeland Security Secretary Jeh Johnson told CNN's Jake Tapper on Sunday's State of the Union.
Johnson said U.S. intelligence and security officials have become "pretty good" at uncovering plots hatched abroad by terrorist groups. But he indicated that the government is facing a new challenge to try to prevent terrorist-inspired attacks planned within the country's borders, including those of the "lone wolf" variety in Florida and California.
"We are safer when it comes to the 9/11-style attack. Our government has become pretty good at detecting plots against the homeland," Johnson said.
"But we've got this new environment and new threat, which makes it harder, and we're now seeing attacks in Orlando and San Bernardino that we've got to protect against. ... This is a new phenomenon."
Johnson indicated that stopping such lone wolf attacks can't be done simply by using traditional government intelligence tools. He urged all Americans to be "vigilant."
Israel's prime minister marked the 15th anniversary by saying his country stands by its "greatest ally, the United States of America."
Benjamin Netanyahu's comments Sunday came two days after a rare American rebuke for statements in which he insisted settlements were not an obstacle to peace and that Palestinians wanted the "ethnic cleansing" of Jews in the West Bank.
U.S. State Department spokesman Elizabeth Trudeau said such terminology was "inappropriate and unhelpful."
Information for this article was contributed by Vera Haller and Brian Bennett of the Los Angeles Times; by Amber Phillips of The Washington Post; and by Joe Mandak, Jennifer Peltz, Verena Dobnik, Lisa Lerer, Tom Hays, Michael Balsamo, Deepti Hajela and staff members of The Associated Press.
A Section on 09/12/2016