Updated at 2:16 p.m. ET
NEW YORK - Marking Osama bin Laden's death where the terrorist inflicted his greatest damage, President Barack Obama soberly laid a wreath Thursday at New York's ground zero and declared to the city and the world, "When we say we will never forget, we mean what we say."
The president closed his eyes and clasped his hands at the outdoor memorial where the twin towers of the World Trade Center once dominated the Manhattan skyline. He shook hands with 9/11 family members and others dressed in black at the site where the skyscrapers were brought down by planes commandeered by bin Laden's followers. Nearly 3,000 people were killed.
The president met privately at the memorial site with about 60 family members from various 9/11 organizations.
Earlier, the president visited the firefighters and police officers whose response to the terror attacks of Sept. 11, 2001, turned them into heroes and symbols of national resolve, but also cost them heavy casualties on that horrific day.
"This is a symbolic site of the extraordinary sacrifice that was made on that terrible day," the president said Thursday at Engine 54, Ladder 4, Battalion 9. The firehouse in New York's theater district lost 15 firefighters on Sept. 11, 2001.
Months before the 10th anniversary of the Sept. 11 attacks, and days after bin Laden was killed in Pakistan by U.S. commandos, Mr. Obama's visit was giving New York its own moment of justice. There was heavy security, but New Yorkers still turned out by the hundreds to gather just southeast of the World Trade Center site and line the roads to watch the president's motorcades.
There were happy faces and flags waved in the crowd though they were cordoned off blocks from where the president entered the ground zero site.
The president's visits with police and firefighters were upbeat, but overall the day did not have a celebratory feel despite the success of the mission to get bin Laden. The mood at ground zero was somber, even sad, as the president stood where the towers had been, seeing the faces of the children who lost parents and adults who lost spouses. As Obama bowed his head, a jetliner screamed by far overhead on a blue-sky day.
Mr. Obama never mentioned bin Laden's name in his brief remarks to firefighters and police.
"What happened on Sunday because of the courage of our military and the outstanding work of our intelligence sent a message around the world but also sent a message here back home," he said at the firehouse.
Mr. Obama said he hoped the outcome brought the firefighters "some comfort," thanked them for their daily work and said they had a president who has "got your back."
At the Pentagon, meanwhile, Vice President Joe Biden led a similar wreath-laying ceremony at the site where another hijacked plane crashed into the nation's military headquarters.
Mr. Obama's visit to New York came as new details emerged of the daring raid on bin Laden's Pakistan compound. A senior defense official said Thursday that only one of the five people killed in the raid was armed and fired a shot an account that differs from original administration portrayals of an intense firefight. The White House also now says bin Laden was unarmed when he was shot, after officials initially said the terrorist was holding a gun or even firing.
Such details perhaps mattered little to New Yorkers who suffered most grievously in the attacks and are now deeply gratified to see bin Laden's demise.
Ahead of Mr. Obama's arrival, Deanne McDonald stood at the northeast corner of the World Trade Center site waving an American flag in each hand and shouting "Obama got Osama! Obama got Osama!"
"God bless the Navy SEALS," said McDonald, 38, from Brooklyn. She took work off on Thursday to wait for the president, saying she was prouder than ever to be an American.
Mr. Obama's New York visit was intended to have a measured tone not a bookend to President George W. Bush's visit after the attacks when Bush took a bullhorn and called out his defiance to the terrorists. Mr. Obama spokesman Jay Carney told reporters traveling with the president on Air Force One that the trip was intended in part "to perhaps help New Yorkers and Americans everywhere to achieve a sense of closure with the death of Osama bin Laden."
The White House didn't want him to appear as though he's exploiting the situation, taking advantage of the families in any way or enjoying some kind of victory lap after bin Laden's death, reports CBS News chief White House correspondent Chip Reid.
The bustling construction site that Mr. Obama visited bears little resemblance to the pit that remained after the rubble of the towers was removed. The emerging skyscraper informally known as Freedom Tower is more than 60 stories high now. Mammoth fountains and reflecting pools mark the footprints of the fallen twin towers.
"I just want to thank him, hug him and thank him and shake his hand," Riches said. "Father to father. Thank you for doing this for me."
Mr. Obama arrived in New York City Thursday afterso the world could see some proof of death. The president said he would not risk giving propaganda to extremists or gloat by publicizing grotesque photos of a terrorist leader shot in the head.
Speaking exclusively to CBS' "60 Minutes," the president said the United States would not "trot out this stuff as trophies... The fact of the matter is, this is somebody who was deserving of the justice that he received."
To those who keep on doubting, Mr. Obama said, "You will not see bin Laden walking on this earth again."
The president sought to handle the moment without being seen as overly celebrating bin Laden's death or aiming to boost his own standing.
Al Qaeda terrorists hijacked jets and flew two of them into the World Trade Center's towers. Both buildings collapsed, trapping thousands inside and also claiming the lives of firefighters and others who had rushed to help. A third plane slammed into the Pentagon. Officials have speculated that a fourth plane had been heading for the U.S. Capitol or perhaps even the White House when it crashed after passengers fought back in Pennsylvania.
A few days later, Bush stood amid the rubble and spoke through a bullhorn. When one worker yelled, "I can't hear you," the president responded: "I can hear you! The rest of the world hears you! And the people and the people who knocked these buildings down will hear all of us soon!"
All these years later, Mr. Obama said this is no time for gloating.
Mr. Obama invited Bush to join him Thursday, but the former president declined.
Heightened security put in place in response to the killing of bin Laden remained for Mr. Obama's visit. Police officials said there were no specific threats against the city but also said they assumed bin Laden's "disciples" might try to avenge his death with a terror attack.