As the commemorations unfolded, the flags around the Washington Monument flew at half-staff, stirring in the southerly breeze.
A former Marine, Tobiath Steinmetz, clad in biblical garb, carried a full-size wooden cross on the Mall.
And Marco Price-Bey, a barber in Southeast Washington giving veterans free haircuts for the day, said, “It’s our social duty to serve and our moral obligation to look out for others.”
The events recalled the morning 12 years earlier when terrorists hijacked four jetliners, flying two into World Trade Center buildings in New York City and one into the Pentagon, and crashing one into a field near Shanksville, Pa.
About 2,800 people were killed in New York and Shanksville, and 184 died at the Pentagon.
“Today we remember not only those who died that September day,” Obama said during a ceremony at the National 9/11 Pentagon Memorial, which followed a moment of silence outside the White House.
“We pay solemn tribute to more than 6,700 patriots who have given their full measure since — military and civilians,” the president said. “We see their legacy in the friendships they forged, the attacks they prevented, the innocent lives they saved.”
“We pray for the memory of all those taken from us — nearly 3,000 innocent souls,” he told victims’ relatives. “Even more than memorials of stone and water, your lives are the greatest tribute to those that we lost.”
In New York, bells tolled as relatives read the names of victims at the memorial plaza on the site where the World Trade Center towers collapsed.
A similar scene played out in Shanksville, where the terrorists crashed a plane as the passengers stormed the hijackers.
On the Mall in Washington, before a ceremony marking the anniversary of the attacks, a small group that included Muslim Americans bickered with a small group of Christian activists over the role and merits of Islam.
A phalanx of park police on motorcycles were on hand to keep the groups separated.
“We’re just regular, God-fearing, Bible-believing, patriotic, red-blooded Americans,” said Ruben Israel, 52, of Los Angeles, who spoke for a group carrying banners that read, “You Need Jesus” and “Repent of Your Wicked Heart of Unbelief.”
“I think every Christian should be offended that they want to have a rally on 9/11,” he said, referring to the Muslims. “We’re here to promote Jesus Christ as the answer to that bloody religion.”
Isa Hodge, 39, of the American Muslim Political Action Committee, said his group had a permit from the National Park Service for the rally.