U.S. shooting horrors

On Dec. 14, heavily armed Adam Lanza shot dead 20 children aged five to 10 and eight adults at Sandy Hook Elementary School in Newtown of Connecticut State.

The shooting spree came after the 20-year-old gunman had first murdered his mother at their home. He fired off more than 100 shots in the barely 10-minute massacre. With his final shot, he killed himself.

The rampage, less than two weeks before Christmas, was the second-deadliest school shooting in U.S. history, exceeded only by the 2007 Virginia Tech massacre that left 32 people dead.

This year, mass shooting crimes have reached a climax in the world's most powerful nation. On April 2, a gunman killed seven people and wounded three others during a shoot-out at a Christian college in Oakland, California. On July 20, a masked gunman killed 12 and wounded 58 when he opened fire on moviegoers at a showing of the new Batman film "The Dark Knight Rises" in Aurora, a suburb of Denver. On August 5, a gunman killed six people during Sunday services at a Sikh temple in Oak Creek, Wisconsin, before being shot dead by police.

Following the Connecticut shooting, President Obama said he was heartbroken and ordered all U.S. flags to be flown at half-mast, signaling it was time to come together and take meaningful action "regardless of politics."