SHANKSVILLE, PA — US President Donald Trump on Tuesday praised the men and women of United Flight 93 for saving countless lives when they struggled with hijackers on Sept. 11, 2001, and called the field where the plane went down a monument to "American defiance."

Commemorating the 17th anniversary of the attacks that destroyed the World Trade Center in New York and struck the Pentagon outside Washington, Trump said the nation shared the grief of the family members whose loved ones were lost that day.

"We grieve together for every mother and father, sister and brother, son and daughter, who was stolen from us at the Twin Towers, the Pentagon and here in this Pennsylvania field," Trump said.

Commemorations also took place in New York and Washington to mark the anniversary of the 9/11 attacks by al Qaeda, in which nearly 3,000 people were killed.

Flight 93 was heading to San Francisco from Newark, New Jersey, when passengers stormed the plane's cockpit and sought to take control from the hijackers. All were killed when the plane crashed in a field, preventing what was thought to be another planned target in Washington.

Family members of Flight 93, some of their voices breaking, read aloud the names of the 40 passengers and crew members who died. Memorial bells tolled.

Trump and his wife, Melania, traveled to the Flight 93 National Memorial from Washington and paused for a moment of reflection while overlooking the field where the plane crashed.

"They boarded the plane as strangers and they entered eternity linked forever as true heroes," Trump said of the passengers and crew.

"This field is now a monument to American defiance. This memorial is now a message to the world: America will never, ever submit to tyranny."

Trump is still dealing with the consequences of that day, with the war in Afghanistan, launched in response to the attacks, now America's longest. He cited the wars in Iraq and Afghanistan in his remarks, saying: "Nearly 7,000 service members have died facing down the menace of radical Islamic terrorism."

In New York, the Bell of Hope rang out at St. Paul's Chapel to mark the moment at 8:46 am when the first of two hijacked planes hit the World Trade Center. The bell has been rung on every anniversary since 2002, when it was presented to New York by the City of London to honor those who died.

Mourners gathered at the National September 11 Memorial plaza in Manhattan for the annual reading of victims' names. Members of the UN Security Council stood for a moment of silence led by US Ambassador Nikki Haley.

REUTER