Republican presidential candidate, former Massachusetts Gov. Mitt Romney, speaks at a campaign event in Bow, N.H., Friday, July 20, 2012. Romney auditions on the international stage next week as he travels to England, Israel and Poland looking to establish credibility as a potential commander in chief in his challenge to President Barack Obama. (AP Photo/Charles Dharapak)

AURORA, Colo. - President Barack Obama arrived in Colorado to deal with the horror of the movie theatre massacre in person Sunday, making a brief stop in a shattered town to comfort families of the victims senselessly gunned down while viewing a blockbuster movie.

Air Force One touched down at Buckley Air Force Base in Aurora in the late afternoon for the president's hastily arranged 2 1/2-hour visit, which included a private meeting with the victims' loved ones and a public comment about the shooting early Friday morning at a busy multiplex. Two of the victims served at the base.

Colorado Gov. John Hickenlooper, Aurora Mayor Steve Hogan and Aurora Police Chief Dan Oates were among those who greeted Obama at Buckley.

Obama met with family members at the University of Colorado Hospital in Aurora, which treated 23 of the people injured in the mass shooting; 10 remain there, seven hurt critically. He said that he told the families of the victims that "all of America and much of the world is thinking about them."

Republican challenger Mitt Romney said Obama's decision to meet with the families was "the right thing."

The impossible-to-understand killings — apparently the work of an unhinged former doctoral student — briefly silenced the presidential campaign over the weekend. Both Obama and Romney cut short their schedules late last week and closed down their television advertising in Colorado out of respect for the victims and their families.

The president planned just a brief visit to the Denver suburb, where the shots rang out at a multiplex theatre early Friday. Twelve of the victims died, 58 were injured.

"I think the president coming in is a wonderful gesture," said Hogan, Aurora's mayor. "He's coming in, really, to have private conversations with the families. I think that's totally appropriate."

Hogan told ABC television's "This Week" that it "certainly means a lot to Aurora to know that the president cares."

After the Colorado stop, Obama is flying to San Francisco, where on Monday he'll begin a previously scheduled three-day campaign trip that includes a speech to the Veterans of Foreign Wars in Reno, Nevada, multiple fundraisers in California, Oregon and Washington state, and a speech to the National Urban League convention in New Orleans.

Aides said Obama received updates Saturday from his homeland security adviser, John Brennan, on the investigation into the shooting and the attempts by authorities to gain access to the suspect's apparently booby-trapped apartment.

For Obama, the Colorado visit was to be his second to the state in just over three weeks. Last month, he flew to Colorado Springs to share the pain of homeowners whose houses had been turned to charred heaps by a record outbreak of wildfires.

Obama and Romney used previously scheduled campaign appearances on Friday to focus attention on the need for national unity in the aftermath of the shootings. Their campaign teams rescheduled Sunday television news show appearances by top aides and surrogates, essentially providing a break in what has been an increasingly negative campaign.

The Colorado rampage injected a new tone into the campaign after Obama and Romney had clashed repeatedly over the economy, health care programs for the elderly, and the Republican candidate's tax returns.

Obama was set to start his second day of events in Florida when the shootings occurred, prompting his team to address the violence at a previously scheduled rally in Fort Myers, Florida, and scrapping an event in suburban Orlando. Obama told supporters in Fort Myers that the shootings served as a "reminder that life is very fragile."

"Our time here is limited and it is precious. And what matters at the end of the day is not the small things, it's not the trivial things," he said. "Ultimately, it's how we choose to treat one another and how we love one another."

Romney echoed Obama's call for unity, saying at a previously scheduled event in Bow, New Hampshire, that he joined with the president and first lady in offering condolences for those "whose lives were shattered in a few moments, a few moments of evil in Colorado."

"The answer is that we can come together. We will show our fellow citizens the good heart of the America we know and love," Romney said.

Yet, beyond the calls for a higher purpose, the shootings could raise the profile of gun rights in the presidential campaign, an issue which has played a minor role so far.

As a senator, Obama voted to leave gun makers and dealers open to civil lawsuits, and as an Illinois state lawmaker he supported a ban on all forms of semiautomatic weapons and tighter state restrictions generally on firearms.

Following the killing of six people and wounding of then-U.S. Rep. Gabrielle Giffords in Tucson, Arizona, in 2011, Obama called for a series of steps to "keep those irresponsible, law-breaking few from getting their hands on a gun in the first place."

Among those steps was a better federal background check system. The administration said Friday that it has indeed improved the amount and quality of information poured into that system, allowing background checks to be more thorough.

But the administration has offered no detailed, public explanation of how it is following up on all of Obama's previous promises, and it had no comment about any need for new legislation.

Romney backed some gun control measures when he was governor of Massachusetts. When he challenged Sen. Edward M. Kennedy in 1994 he declared, "I don't line up with the NRA." In April, Romney told the National Rifle Association, an influential lobbying group representing gun owners, he was a guardian of the Second Amendment of the U.S. Constitution. That amendment guarantees the right to bear arms.

Romney spokeswoman Andrea Saul said the Republican candidate believes that the "best way to prevent gun violence is to vigorously enforce our laws."

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Associated Press writers Julie Pace in Aurora, Colorado, and Steven R. Hurst in Washington, contributed to this report.

News from © The Associated Press, 2012