Americans on Tuesday mark the 17th anniversary of the Sept. 11, 2001 terrorist attacks that killed almost 3,000 people in New York, Virginia and Pennsylvania.
President Donald Trump is attending a ceremony at the 9/11 memorial in Shanksville, Pennsylvania, near where United Airlines Flight 93 crashed after passengers retook control from the al-Qaida-affiliated terrorists who had hijacked the plane.
In the annual presidential proclamation declaring September 11 as Patriot Day, Trump said the "evil acts" did not crush the country's spirit or its commitment to freedom.
"We come together, today, to recall this timeless truth: When America is united, no force on Earth can break us apart. Our values endure; our people thrive; our nation prevails, and the memory of our loved ones never fades," he said.
Just outside Washington, Vice President Mike Pence is attending a ceremony at the Pentagon for families of those killed when a hijacked plane crashed into the building.
And in New York, hundreds of survivors and family members of those killed will gathered at Ground Zero, where the Twin Towers of the World Trade Center stood before two hijacked commercial flights brought them down. Twin beams of light will be projected into the sky to memorialize those lost in the attacks.
The hijackings were carried out by 19 men affiliated with al-Qaida. The deadliest attack on American soil since Pearl Harbor in 1944, the events of Sept. 11 permanently changed America's perception of security and prompted then-President George W. Bush to declare war on terrorism and invade Afghanistan.
Almost two decades later, the anniversary remains a painful reminder for the families of those who died.
Mary Fetchet's son Brad was working in the South Tower of the World Trade Center when the first plane hit.
"My son called my husband to let him know he was okay, and just to remind him that he was in the second tower," Fetchet told VOA.
After her husband called her at work to tell her Brad was alive, Fetchet walked into an adjoining building. As she entered the room, she saw the second plane hitting the other tower on television.
"Of course I was hoping, trying to calculate where he was in the building, and if he had in fact had time between the time he called my husband to be below the line where the plane entered the building," Fetchet said.
Fetchet went home after that, hoping for a call from her son that never came. Near the end of September, she held a memorial for Brad.
In the wake of the attacks, Fetchet organized groups of survivors and the families who lost loved ones.
"I pretty immediately realized that the families who'd lived around the country and in 90 countries abroad had challenges in accessing information. And many decisions were being made that impacted them directly," Fetchet said.
The realization led her to create the charity Voices of September 11th, which provides services to families affected by the tragedy, such as sponsoring support groups and helping identify the remains of loved ones. The organization has also expanded to provide services to communities impacted by violence around the world.
"We've learned so much over the last 17 years," Fetchet said. "There seems to be no end to the acts of terrorism and mass violence both here in the United States and abroad."