And he pledged in a video that he'd do everything in his power as president to address safety, mental health issues and the culture of violence that may have contributed to the tragedy.

"If there's even one thing we can do as a country to protect our children, we have a responsibility to try," the president said.

The video was a response to the "We The People" petitions that have been submitted to the White House in the wake of the Newtown tragedy. In it, Obama urges viewers to call Congress "as many times as it takes" to push for gun restrictions.