WORLD'S WORST MASS SHOOTINGS
A gunman at a Connecticut elementary school has killed 27 people, including 18 children - one of the world's worst mass shootings. Here are some others:
August 5 2012: Army veteran Wade Michael Page kills five men and one woman and wounds three other people, including a police officer, before taking his own life at the Sikh Temple of Wisconsin outside Milwaukee.
July 20 2012: At least 12 people are killed when a gunman enters a cinema in Aurora, Colorado, releases a canister of gas and then opens fire during the opening night of the Batman movie The Dark Knight Rises. James Holmes, a 24-year-old former graduate student at the University of Colorado, has been charged over the deaths.
March 11 2012: Sixteen Afghan villagers, including nine children, are killed during a pre-dawn attack. Army prosecutors have charged Staff Sergeant Robert Bales, 39.