US school shooting horror: A nation mourns

US President Barack Obama wiped away tears and struggled to compose himself as he mourned the dead in the Connecticut school shooting, and promised ‘‘meaningful’’ action to stop gun tragedies.

‘‘The majority of those who died today were children, beautiful little kids between the ages of five and ten years old,’’ Obama said.

‘‘They had their entire lives ahead of them, birthdays, graduations, weddings, kids of their own.’’

Up until a few days ago, the biggest crime being reported in sleepy Newtown, Connecticut was the vandalism of the historic cemetery overlooking Elm Drive.

Residents were shocked by the vandalism of the old headstones in the Newtown Village Cemetary, which was reported last week in the town's 133-year old newpaper, The Newtown Bee.

The Sandy Hook Elementary School massacre sent shockwaves through the community and around the world, leaving 20 children and several adults dead, a town shattered, a nation in mourning and the world asking how such a tragedy could happen.

Emotions were running high in Colorado, which was rocked by the 1999 Columbine High School and - less than six months ago - the movie theatre shooting in the Denver suburb of Aurora.

The latest in a line of shooting tragedies has reignited calls from gun control activists for laws restricting access to weapons.

"Until we get our acts together and stop making these ... weapons available, this is going to keep happening," said an angry Tom Teves, whose son Alex was killed in the theatre shooting last July.

The 20-year-old killer, identified by a law enforcement official as Adam Lanza, carried out the attack with two handguns. A high-powered .223-calibre rifle was found in the back of a car. The official spoke on the condition of anonymity because they were not authorised to speak on the record about the unfolding investigation.

This week, Colorado Gov. John Hickenlooper generated a storm of debate after declaring that it was time to start debating gun control measures. And on Friday, Hickenlooper told reporters there's no use waiting until news coverage fades.

"We can't postpone the discussion on a national level every time there's a shooting. They're too often," he said.

A visibly emotional Obama seemed willing to renew debate, calling for "meaningful action" to prevent similar shootings, but he was not specific. During Obama's time in office, mass shootings have shaken communities in Wisconsin, Texas and Colorado.

A minister from California who was in Washington as part of a religious-based effort to speak out against gun violence called on Obama to take a stand for gun control before his State of the Union address in January, or during it.

"Platitudes and condolences do not help. We need action," the Rev. Michael McBride said.