Sandy Hook shooting: Obama vows to use power of presidency to thwart massacres

At a prayer service in Newtown, Conn., Sunday night, President Obama said he would gather law enforcement and mental health officials to address the kind of gun violence that struck Sandy Hook Elementary School. 'We can't tolerate this anymore,' he said.

President Obama told a prayer vigil in massacre-devastated Newtown, Conn., Sunday evening that "I'll use whatever power this office holds … [to prevent] more tragedies like this, because what choice do we have?"

Coming after what Mr. Obama has said was his most difficult day in office when a gunman on Friday killed 20 first graders and six school professionals in this quiet, close-knit New England town, the promise rang out as perhaps the boldest of his presidency as he vowed to head up a national soul-searching effort likely to involve examination of school security, mental health policy, and gun laws.

"We can't accept events like this as routine," Obama said after an emotional interfaith vigil. "Are we really prepared to say that we're powerless in the face of such carnage, that politics are too hard, are we prepared to say that such violence visited upon our children year after year is the price of our freedom?"

When tragedy strikes: a prayerful response to the shootings in Connecticut

The vigil marked the fourth time Obama has mourned victims of mass shootings. They include shootings at Fort Hood, Texas, Tucson, Arizona, and, earlier this year, Aurora, Colorado. Obama painted a picture of a country grieving for innocent children, first responders who came upon a horrific scene, and the parents and relatives left behind.

After meeting with victims' families and police and firefighters who rushed into the school only to be met by the deadly results of unspeakable mayhem, Obama spoke for about 20 minutes at a packed Newtown High School. In meeting places and taverns around the town applause rang out after an unusual speech that meshed Bible verses, remembrances of children and teachers, with an almost angry resolve that left those watching in stunned silence, followed by applause and a standing ovation. "We love you, Barry," one woman at a local tavern called out.

On Friday, a 20-year-old Newtown local, Adam Lanza, killed his mother, then drove five miles to Sandy Hook Elementary School, where he forced his way in and entered two classrooms close to the entrance, firing rapid fusillades into groups of first graders and their teachers. Twelve girls, eight boys, and six female staff, including the principal, died. Police say Lanza then turned a gun on himself as police arrived.

The sheer brutality of the lingering question – why? – caused a close-knit community to recede into churches, homes, and crisis centers on Sunday to grieve and seek understanding. "No media" signs were everywhere. Meanwhile, hundreds of people ventured into the town to place teddy bears into a line of Christmas trees and place flowers on makeshift memorials that burned into the night.

"I am very mindful that mere words cannot match the depth of your sorrow, nor can they heal your wounded hearts," Obama said. "I can only hope it helps for you to know that you're not alone in your grief, that our world, too, has been torn apart, that all across this land of ours we have wept with you … and we've pulled our children tight. As these difficult days have unfolded, you've also inspired us with stories of strength and resolve and sacrifice. That is how we will remember Newtown."

When tragedy strikes: a prayerful response to the shootings in Connecticut