Reprising his role of the nation's consoler in chief after yet another mass shooting, Obama issued a call to action on gun control measures that failed to pass earlier this year and show no new momentum in the wake of last week's rampage at a military installation just blocks from the Capitol.
"Our tears are not enough," Obama told thousands gathered to mourn at the Marine Barracks. "Our words and our prayers are not enough. If we really want to honor these 12 men and women, if we really want to be a country where we can go to work and go to school and walk our streets free from senseless violence without so many lives being stolen by a bullet from a gun, then we're going to have to change."
Obama said when such senseless deaths strike in America, "it ought to be a shock to all of us, it ought to obsess us. It ought to lead to some sort of transformation."
But, Obama said, "nothing happens. Alongside the anguish of these American families, alongside the accumulated outrage so many of us feel, sometimes I fear there is a creeping resignation that these tragedies are just somehow the way it is, that this is somehow the new normal. We cannot accept this. As Americans bound in grief and love, we must insist here today there is nothing normal about innocent men and women being gunned down where they work."
He said no other advanced nation endures the kind of gun violence seen in the United States, and blamed mass shootings in America on laws that fail "to keep guns out of the hands of criminals and dangerous people."
"What's different in America is it's easy to get your hands on a gun," he said. He acknowledged "the politics are difficult," a lesson he learned after failing to get expanded background checks for gun buyers through the Democratic-controlled Senate this spring. Obama had proposed the measure after the shooting at Connecticut's Sandy Hook Elementary School killed 20 first-graders and six staff.
"And that's sometimes where the resignation comes from: the sense that our politics are frozen and that nothing will change. Well, I cannot accept that," Obama said. "By now, though, it should be clear that the change we need will not come from Washington, even when tragedy strikes Washington. Change will come the only way it ever has come, and that's from the American people."
Obama joined military leaders in eulogizing the dozen victims killed in last Monday's shooting, speaking from the parade grounds at the Marine Barracks, a site personally selected by Thomas Jefferson because of its close marching distance to the Navy Yard. The memorial service came on the first day of fall, which shone brightly in Washington, with sun sparkling off the instruments being played by the Navy Band and the gold dress uniform buttons worn by so many in the crowd.
The invitation-only crowd included around 4,000 mourners, with the victims' tearful, black-clad family members directly in front of the speakers' stage. The president and first lady Michelle Obama met privately with the families before the service, White House officials said.
Authorities say their loved ones' lives were taken Monday by shotgun-wielding Aaron Alexis, a 34-year-old former Navy reservist and information technology contractor who struggled with mental illness. Police killed Alexis in a gun battle.
Obama said it's clear from the Navy Yard shooting that the country needs to do a better job to secure its military facilities and improve mental health services, but also address gun laws.
"I do not accept that we cannot find a common-sense way to preserve our traditions, including our basic Second Amendment freedoms and the rights of law-abiding gun owners while at the same time reducing the gun violence that unleashes so much mayhem on a regular basis," Obama said. "It may not happen tomorrow and it may not happen this week, it may not happen next month. But it will happen because it is the change that we need. And it's a change overwhelmingly supported by the majority of Americans."
Earlier Sunday, National Rifle Association Executive Vice President Wayne LaPierre rejected any call for gun control. "The problem is there weren't enough good guys with guns," LaPierre said on NBC's "Meet the Press."
The military leaders who spoke before Obama at the memorial service, including Defense Secretary Chuck Hagel, Navy Secretary Ray Mabus and Adm. Jonathan Greenert, chief of naval operations, avoided any mention of gun control as they remembered the victims as heroes. But Washington Mayor Vincent Gray spoke forcefully for action, mentioning that one of the Navy Yard victims, Arthur Daniels, had already lost his 14-year-old son to gun violence and citing the string of mass public shootings in recent years.
"Why is it that these tragic consequences and these tragic occurrences never seem to move us any closer to ensuring that guns don't get into the hands of criminals or mentally unstable people?" Gray asked. "I don't know the answer. But I do know this - that this time it happened within the view of our Capitol dome, and I for one will not be silenced about the fact the time has come for action."
The service ended with a bugler playing taps and singing of the Navy hymn after a reading of the names of the fallen, who ranged in age from 46 to 73 and included civilian employees and contractors. Eight people were also hurt, including a police officer and two others who suffered gunshot wounds.
Obama also mentioned each victim - describing them in turn for their love of their family, their service to their community and their passions, ranging from classic cars to the Washington Capitals hockey team.
"Once more our hearts are broken. Once more we ask, Why?" Obama said.
Associated Press writers Philip Elliott, Jessica Gresko and Stacy A. Anderson contributed to this report.