President Obama said Thursday evening that the "routine" nature of mass shootings in America will continue unless the country's politics changes.

"This is a political choice that we make, to allow this to happen every few months in America," said the president, who was visibly frustrated as he delivered a statement on Thursday's mass shooting in Roseburg, Ore.

Obama has frequently railed against Congress's refusal to pass additional gun control measures in an effort to curb mass shootings, especially in the wake of the Dec. 14, 2012, massacre of 20 students and six teachers at Sandy Hook Elementary School in Newtown, Conn. But on Thursday he delivered remarks in which he veered from anger to incredulity as he described his amazement that a slew of horrific attacks had failed to spur a response from Washington's political establishment.

"There’s been another mass shooting in America -- this time, in a community college in Oregon," he declared flatly at the outset of his comments in the Brady Press Briefing Room, named for President Ronald Reagan's press secretary who was shot during a March 1981 assassination attempt on the president. "That means there’s another community stunned with grief, and communities across the country are forced to relive their own anguish, and parents across the country who are scared because they know it might have been their families and their children."

"But as I said just a few months ago," he said, his voice rising to a higher pitch, "and I said a few months before that, and I said each time we see one of these mass shootings, our thoughts and prayers are not enough. It’s not enough."

"It does not capture the heartache and grief and anger that we should feel," he said, punctuating the word "anger" with added emphasis. "And it does nothing to prevent this carnage from being inflicted some place else in America."

After noting how the country is willing to devote enormous resources to address other threats to human life, ranging from terrorist strikes to unsafe bridges, Obama questioned why there is a different response when it comes to guns.

"So the notion that gun violence is somehow different? That our freedom, and our Constitution, prohibits any modest regulation of how we use a deadly weapon, when there are law-abiding gun owners all across the country who could hunt and protect their families and do everything they could do under such regulations?" he asked. "Doesn’t make sense."

Obama bemoaned the fact that these tragedies have become so frequent, he said, that they no longer shocked the public. He urged media outlets to list the number of Americans who die each year from terrorist attacks against the number who are killed by guns, to show how much greater a threat gun violence poses to the country.

"Somehow this has become routine," he said, looking a bit incredulous at the prospect. "The reporting is routine. My response here at this podium ends up being routine."

Rather than listing the numerous tragedies that have occurred during his time in office -- in Newtown, in Charleston, S.C., where a gunman killed nine parishioners in an African American church in June, and in countless other places -- he noted that during an interview in July he lamented that the United States was the "one advanced nation on earth" that has not adopted "common-sense gun safety measures" in the face of multiple mass shootings.

"And later that day there was a mass shooting in a movie theater in Lafayette, Louisiana. That day," he said, his voice strained.

At times, his tone turned combative. "Right now I can imagine the press releases being cranked out: 'We need more guns,' they'll argue. 'Fewer gun safety laws.'"

"Does anybody really believe that?" he said. "There are scores of responsible gun owners in this country, they know that’s not true."

While the president said that the 26 year-old alleged shooter at Umpqua Community College on Thursday was mentally ill -- "it’s fair to say anybody who does this has a sickness in their minds, regardless of what they think their motivations may be" -- he also said other advanced countries with mentally ill citizens do not suffer the same fatalities.

"I’d ask the American people to think how they can get our government to change these laws, and to save lives, and to let young people grow up. And that will require a change of politics on this issue," he said, adding that "this cause of continuing death for innocent people should be a factor" when voters choose which elected officials they want to support at the ballot box.

"And each time this happens," he vowed, "I’m going to bring this up. Each time this happens, I am going to say we can actually do something about it, but we’re going to have to change our laws."

"I hope and pray that I don’t have to come out again during my tenure as president to offer my condolences to families in these circumstances. But based on my experience as president," he said, looking grim, "I can’t guarantee that. And that’s terrible to say. And it can change."

And after uttering a prayer for the victims and their families, the president turned and walked out of the room. The press corps sat in their seats, silent.