The three men represented the Fire Department, the Police Department and Port Authority, which together lost more than 400 people in the terrorist attack. Later, the anniversary ceremony at ground zero paused for two moments of silence - the first two of four commemorating the times when each jetliner crashed into a tower and when each skyscraper collapsed.
"We come here to honor those that we lost, and to remember this day with sorrow," Mayor Michael Bloomberg said.
Across the nation, the tolling of bells, the laying of wreaths and, in many places, moments with no words at all were planned for the second anniversary of the terrorist assault that killed more than 3,000 people.
In lower Manhattan, at the site where the World Trade Center once stood, 200 children whose relatives were among the 2,792 began the solemn, careful task of reading the names of the victims in a morning ceremony.
"I know I'm very proud of my children," said Lynn Morris, whose husband, Seth Allan Morris, died Sept. 11, 2001, and whose two children, 11-year-old Madilynn and 9-year-old Kyle, were reading names. "It's amazing the strength that they have developed over the years."
Families began arriving well before the ceremony, many wearing ribbons of white or black, symbolizing mourning, or yellow, for hope. They also carried flowers - daisies, petunias and roses to leave at the site during the ceremony.
The footprint of the trade center's north tower was outlined by a 4-foot fence draped with banners bearing drawings and messages painted by children of the victims.
One of them was a simple red heart, outlined in black, with the inscription: "To my Dad, Steve Chucknick. Your in my heart forever. Love always, your son Steven."
A silent vigil began Wednesday night in New York at St. Paul's Chapel, once in the shadow of the trade center. The Rev. Julie Taylor, 33, who volunteered at the chapel two years ago, said healing is a lifelong process. "There's no getting over it; there's just getting through it," she said.
At sunrise Thursday, about 200 people sat quietly at an ecumenical service at a small park not far from ground zero that included a violinist, readings of poems and songs by a children's choir.
"I was hoping to get a couple minutes to face up to all the emotions of the day and to continue the process of trying to adjust," said Nathaniel Hupert, a 37-year-old public health researcher."
The ground zero ceremony, lasting about 3 1/2 hours, was to fall silent at the four moments when the terror peaked two years ago: the time of impact of each plane that flew into the trade center, and the time of each tower's collapse.
In Washington, President Bush described his thoughts as he left a morning church service.
"We remember the lives lost," he said. "We remember the heroic deeds. We remember the compassion, the decency of our fellow citizens on that terrible day.
"We pray for the husbands and wives, the moms and dads and the sons and daughters and loved ones ... we pray for strength and wisdom."
Memorials at other Sept. 11 sites were keyed on each place's moment of attack. A ceremony at the Pentagon was to include a moment of silence at 9:37 a.m., when the impact of a jetliner killed 184 people.
And in southwest Pennsylvania, rural hamlets were to toll bells to mark the time when the fourth hijacked plane plunged into a field there, killing the 40 passengers and crew who were later hailed as heroes for trying to stop more catastrophe.
Elsewhere in the nation, reminders of life, death and peace were set to commemorate Sept. 11, 2001.
In Toledo, Ohio, white doves were to be released after the reading of victims' names. In Massachusetts and Hawaii, bells were to peal to remember the dead.
Twisted steel taken from the ruins and shipped to other states for memorials was to be at the center of ceremonies from North Dakota to Florida to a New Mexico church that uses two trade center beams as part of its bell tower.
And in Tampa, Fla., motorcycle riders were to raise money for the families of police, firefighters and U.S. Special Operations troops who have died in the war on terrorism.
"It helps bring people together, and it helps us feel united," spokeswoman Elaine Diaz said.
The ground zero commemoration, similar to last year's, was to feature readings by Bloomberg, former Mayor Rudolph Giuliani, New York Gov. George Pataki and New Jersey Gov. James McGreevey.
Giuliani said before the ceremony that he still wakes up at night thinking about that day.
At sunset, two light beams pointing skyward were to be switched on, evoking the image of the twin towers in a reprise of a popular monthlong memorial unveiled in March 2002.
But the centerpiece of the ground zero remembrance was the children. Some of the 200 reading names spent the weeks leading to the anniversary practicing the pronunciations on their section of the list.
Lynn Morris looked up articles so that Madilynn and Kyle could match faces to the names. Madilynn was reading 14 names, finishing with that of her father, who was 35 and worked at Cantor Fitzgerald in the trade center.
"I thought it would be a good way to honor my dad," Madilynn said, "and to honor the other people."
World Pauses to Remember Sept. 11 Attacks
Some planted trees to remember fallen compatriots. Others laid wreaths. Some simply mourned quietly as the strains of trumpets echoed over memorial services. Across the world, people and governments marked the second anniversary of the Sept. 11 attacks on Thursday with prayers, promises to continue fighting terrorism - and reflections on the changes that the 2001 attacks have wrought internationally.
At Yokosuka Naval Base just south of Tokyo, U.S. military personnel held a wreath-laying service. In Baghdad, the U.S. administrator for Iraq and the commander of American forces in the country joined about 100 civilians and soldiers for a moment of silence Thursday at deposed leader Saddam Hussein's former Republican Palace in Baghdad.
L. Paul Bremer and Lt. Gen. Ricardo Sanchez stood with the others to bow their heads as a Scottish bagpiper played "Amazing Grace."
"Let us attune our hearts to the voices crying out from the Sept. 11, 2001, compelling us to eradicate terrorism in our world and restore justice and dignity to creation," U.S. Army chaplain Col. Frank Wismer said.
In Australia, hundreds of expatriate Americans and volunteers gathered in a Sydney park to plant some 3,000 trees in remembrance of those who died in the attacks, among them at least 10 Australians.
"It's painful, but it's pain you have to lock away and get on with your life," said Antony Milne, a manager of the World Trade Center's Windows on the World restaurant who moved to Australia after the attacks. "If you allow yourself to stay permanently depressed then the terrorists have won."
At the U.S. Embassy in the Philippines, U.S. Charge d' Affaires Joseph Mussomeli laid a wreath at the base of the mission's flagpole, where the U.S. flag was at half staff. Filipino soldiers played the trumpet as Mussomeli and an American soldier stood at attention.
Australian Prime Minister John Howard warned the battle against terrorists would not end anytime soon.
"This war against terrorism is likely to go on for years and nobody can regard themselves as beyond the reach of terrorism," Howard told Sky News Television. "We need to find ways of further cooperation, particularly at a police and intelligence level."
Howard spoke a day after an Indonesian court sentenced the convicted mastermind of last October's Bali bombings to face a firing squad.
The blasts killed 202 people, including 88 Australians, and was the worst terrorist strike since the Sept. 11 attacks in New York and Washington. Authorities have blamed the Bali bombings on the al-Qaida-linked Jemaah Islamiyah group.
President Bush sent a letter to the Ausralian government expressing condolences over the 10 Australians who died in the Sept. 11 attacks.
It concluded: "Our struggle to rid the world of terror continues and it is a living monument to our fellow countrymen, mine and yours, whose lives were taken on the 11th of September, 2001."
In China's Muslim northwest, the regional Communist Party secretary seized the occasion of the Sept. 11 anniversary to warn that separatists in the country's Xinjiang region were getting training from international terrorists, including at "several training camps in Pakistan."
"We have found some training camps in Xinjiang after the Sept. 11 incident, but not many," he said, adding that the government's successful efforts to battle forces opposed to Beijing's rule were being undermined by assistance from the terrorists abroad.
Across Japan, people paid their respects at memorials to the thousands, including 24 Japanese, who perished.
"The threat of international terrorism still remains serious," Chief Cabinet Secretary Yasuo Fukuda told reporters. "Japan will further strengthen cooperation with other countries and continue to tackle the problem."
Half of the Japanese who were killed worked for Fuji Bank - renamed Mizuho after a merger - which had 700 employees in the World Trade Center. Six Americans working for the bank died along with the 12 Japanese.
Yasushi Miyama, a Mizuho Financial Group spokesman, said memorials at his company would be personal.
In South Korea, police beefed up security at airports, military bases and embassies.
Although no official memorials were planned, authorities wary of possible attacks during a five-day national thanksgiving holiday added 257 police officers to the 1,243 guarding the U.S. Embassy in downtown Seoul and U.S. military facilities across the country.
Police switched to round-the-clock patrols at the British Embassy in Seoul, from once every two hours, and extra security was ordered for other embassies and diplomatic residences in the capital, according to national police agency officials quoted by Yonhap news agency.
In Malaysia's capital, Kuala Lumpur, people entering the world's tallest buildings, the Petronas Twin Towers, had their bags checked, but no extra security was in place Thursday.
200 Gather for Ground Zero Prayer Service
As the sun rose on the second anniversary of the World Trade Center attack, about 200 people gathered in quiet prayer at a waterfront park near where the twin towers once stood.
"I don't know if we'll ever heal," said Roberto Brozen, 57, who lives near the southern tip of Manhattan. He said he was reminded of "how fragile we are and how important we are to each other."
Violinist Jennifer Koh opened the ecumenical sunrise service Thursday with Bach's "Chaconne." The performance was followed by a reading of "The Names," a poem by Poet Laureate Billy Collins.
"Two years later, we still ponder but cannot answer. Each life lost was a price too great," said Timothy Carey, president of the Battery Park City Authority, which owns 92 acres of residential and commercial property near ground zero.
Manhattan Borough President C. Virginia Fields described New Yorkers' sorrow - and their resolve.
"Two years are but the tiniest speck of sand in the hourglass of history," Fields said, "yet the events of that day resonate so soundly that all of us to one degree or another experience a deep sense of sadness and tremendous pride together with the resolve to go forward and rebuild our lives and our city."