David Jackson

USA TODAY

President Obama said Tuesday the nation should do "some soul-searching": over its epidemic of deadly gun violence and "should be ashamed" it has been unable to address it.

"We're the only developed country on Earth where this happens," Obama said during a question-and-answer session on the social media website Tumblr.

"And it happens now once a week," Obama added. "And it's a one-day story. There's no place else like this."

While most of the Tumblr questions concerned the president's student loan programs, and higher education in general, Obama turned emotional when one user asked about school shootings. Obama's comments came just a few hours after the shooting death of a high school student in Oregon.

His "biggest frustration" as president, Obama said, has been that "this society has not been willing to take some basic steps" to keep guns away from people who "can do just unbelievable damage."

The president again criticized Congress for blocking a proposal to expand background checks for gun buyers and said too many lawmakers are "terrified" of the National Rifle Association and other gun rights groups.

While "our levels of gun violence are off the charts," Obama said, the American people themselves have to demand new laws: "If public opinion does not demand change in Congress, it will not change."

Opponents of various gun control proposals said they would be ineffective, and some threaten Second Amendment ownership rights. They also said shootings are a mental health issue, an argument that Obama disputed.

"The United States does not have a monopoly on crazy people," Obama said.

Some highlights from the Tumblr session:

5:07 p.m. -- Over and out: "I've had a great time," Obama tells Tumblr users.

5:05 p.m. -- Obama says he knows one thing he'll do after his second term is over: "I'll be on a beach somewhere."

But that won't last long, he adds, saying he wants to work with young people among other things during his post-presidency.

"Guard against cynicism," Obama tells Tumblr users.

5 p.m. -- The topic of school shootings comes up, as a questioner says he knew one of the victims in the recent deadly shooting spree in California.

Obama says the nation has to figure out a way to keep guns out of the hands of mentally unstable people.

He notes that Australia enacted gun control laws after a single mass shooting, and hasn't had one since.

While some people say mental illness is the problem, Obama said "the United States does not have a monopoly on crazy people."

The problem is availability of guns, Obama said, and "this country has to do a lot of soul searching."

4:51 p.m. -- Another issue surfaces: A proposed increase in the minimum wage. Obama talks about the need for more vocational education, from plumbers to carpenters.

4:45 p.m. -- Obama urges Tumblr voters to support a Senate Democratic plan that would, theoretically, help students lower debt loads by using new government loans -- at lower interest rates -- to pay off existing private loans. Republicans call the plan a gimmick, and have vowed to block it.

4:42 p.m. -- Obama discusses his administration's plans for college "scorecards," ranking schools in various ways.

4:37 p.m. -- Tumblr users are asking Obama for career advice, and what kinds of college majors they should pursue.

Obama talks up math and science, but says everybody is different, and people should pursue work "at something you care deeply about."

4:32 p.m. -- Obama stresses the need for more math and science education, while joking about the fact that he was a humanities major.

"The thing about humanities is you could kind of talk your way through classes," Obama notes at one point.

He adds that getting a math or science education "doesn't preclude you from writing haiku at some point."

4:28 p.m. -- Obama highlights the key part of his student debt relief program: Payments can be capped at 10% of income. He signed an executive order Monday for an expansion of that rule.

Not a lot of people know about this program, Obama says, and "I hope that the Tumblr community spreads the word."

4:25 p.m. -- Early questions focus on the rising costs of college -- and one likens Obama's proposals to help with loan repayments to "a band aid on a broken leg."

Obama also cracks wise about the Tumblr handle of one questioner: "Haiku Moon." It could be her real name, Obama muses, adding that "that's a cool name."

4:15 p.m.-- We begin about 15 minutes late, and President Obama explains his reasons for doing Tumblr.

"We are constantly looking for new ways to reach audiences," Obama says, especially young people.

Obama is seated in a chair, facing Tumblr founder and CEO David Karp, who is the moderator. They are in front of a large flat screen television.