NEW YORK (AP) - As bells tolled solemnly, Americans marked the 12th anniversary of the Sept. 11 terrorist attacks on Wednesday with the reading of the names, moments of silence and serene music that have become tradition.
At a morning ceremony on the 2-year-old memorial plaza at the site of the World Trade Center, relatives recited the names of the nearly 3,000 people who died when hijacked jets crashed into the twin towers and the Pentagon and near Shanksville, Pa., as well as the 1993 trade center bombing victims' names.
In Washington, President Barak Obama, joined by first lady Michelle Obama, Vice President Joe Biden and wife Jill Biden, and members of the White House staff, walked out to the South Lawn at 8:46 a.m. - the moment the first plane struck the south tower in New York. Another jetliner struck the Pentagon at 9:37 a.m.
The World Trade Center Flag is presented as friends and relatives of the victims of the 9/11 terrorist attacks gather at the National September 11 Memorial at the World Trade Center site, Wednesday, Sept. 11, 2013, for a ceremony marking the 12th anniversary of the attacks in New York.
"It is an honor to be with you here again to remember the tragedy of 12 Septembers ago, to honor the greatness of all who responded and to stand with those who still grieve and to provide them some measure of comfort once more," Obama said. "Together we pause and we give humble thanks as families and as a nation."
At the site in lower Manhattan, friends and families silently held up photos of the deceased. Others wept.
"Daddy, I miss you so much, and I think about you every day," Christina Aceto said of her father, Richard Anthony Aceto. "You were more than just my daddy, you were my best friend."
Bells tolled to mark the second plane hitting the second tower and the moments when the towers fell. Near the memorial plaza, police barricades were blocking access to the site, even as life around the World Trade Center looked like any other morning, with workers rushing to their jobs and construction cranes looming over the area.
"As time passes and our family grows, our children remind us of you," Angilic Casalduc said of her mother, Vivian Casalduc. "We miss you."
Loved ones milled around the memorial site, making rubbings of names, putting flowers by the names of victims and weeping, arm-in-arm. Former Gov. George Pataki, New Jersey Gov. Chris Christie and others were in attendance. Continuing a decision made last year, no politicians will speak, including Mayor Michael Bloomberg, who was watching the ceremony for his final time in office.
Over his years as mayor and chairman of the National Sept. 11 Memorial & Museum, Bloomberg has sometimes tangled with victims' relatives, religious leaders and other elected officials over an event steeped in symbolism and emotion. But his administration has largely succeeded at its goal of keeping the commemoration centered on the attacks' victims and their families and relatively free of political image-making.
"Joe, we honor you today and all those lost on Sept. 11," said Kathleen O'Shea, whose nephew Joseph Gullickson was a firefighter in Brooklyn. "Everyone sends their love and asks that you continue to watch over us all, especially your wife."
Memorial organizers expect to take primary responsibility for the ceremony next year and say they plan to continue concentrating the event on victims' loved ones, even as the forthcoming museum creates a new, broader framework for remembering 9/11.
"As things evolve in the future, the focus on the remembrance is going to stay sacrosanct," memorial President Joe Daniels said.
Karen Hinson of Seaford, N.Y., who lost her 34-year-old brother, Michael Wittenstein, a Cantor Fitzgerald employee, said she would like the annual ceremony to be "more low-key, more private" as the years go by.
The 12th anniversary arrives amid changes at the Flight 93 National Memorial in Shanksville, where officials gathered Tuesday to herald the start of construction on a visitor center. At the Pentagon, plans call for a morning ceremony for victims' relatives and survivors of the attacks and an afternoon observance for Pentagon workers.
Around the world, thousands of volunteers have pledged to do good deeds, honoring an anniversary that was designated a National Day of Service and Remembrance in 2009.
When Bloomberg and Pataki announced the plans for the first anniversary in 2002, the mayor said the "intent is to have a day of observances that are simple and powerful."
His role hasn't always been comfortable. When the ceremony was shifted to nearby Zuccotti Park in 2007 because of rebuilding at the trade center site, some victims' relatives threatened to boycott the occasion. The lead-up to the 10th anniversary brought pressure to invite more political figures and to include clergy in the ceremony.
By next year's anniversary, Bloomberg will be out of office, and the museum is expected to be open beneath the memorial plaza.
While the memorial honors those killed, the museum is intended to present a broader picture of 9/11, including the experiences of survivors and first responders.
But the organizers expect they "will always keep the focus on the families on the anniversary," Daniels said. That focus was clear as relatives gathered last September on the tree-laden plaza, where a smaller crowd was gathering Wednesday - only friends and family of the victims were allowed.
Bruni Sandolval carried a large photo of childhood friend Nereida DeJesus, a victim.
"We grew up together on the Lower East Side and I come every year with her family," she said. "Coming here is peaceful in a way."
Denise Matuza, who lost her husband on Sept. 11, said people ask her why she still comes to the service with her three sons.
"It doesn't make us feel good to stay home," she said. Her husband called after the towers were struck. "He said a plane hit the building, they were finding their way out, he'd be home in a little while. I just waited and waited," she said.
"A few days later I found an email he had sent that they couldn't get out."