The shooting at a Connecticut elementary school Friday is among the world's worst mass shootings. Here are some others:
July 20, 2012: Twelve people are killed when a gunman enters an Aurora, Colo., movie theater, releases a canister of gas and then opens fire during 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 in the deaths.
April 2, 2012: A gunman killed seven people in a rampage at a California Christian university. Jongjin Kim, the Oikos University, said the suspect, One Goh, was angry because administrators refused to grant him a full tuition refund after he dropped out of the nursing program.
March 11, 2012: Sixteen Afghan villagers, including nine children, are killed during a predawn attack in which Army prosecutors have charged Staff Sgt. Robert Bales, 39.
July 22, 2011: Confessed mass killer Anders Behring Breivik kills 77 in Norway in twin attacks: a bombing in downtown Oslo and a shooting massacre at a youth camp outside the capital. The self-styled anti-Muslim militant admitted both attacks.
Jan. 8, 2011: A gunman kills six people and wounds 13 others, including then-U.S. Rep. Gabrielle Giffords, in a shooting spree outside a grocery store in Tucson, Ariz. Doctors say Jared Lee Loughner, who has been sentenced to life in prison, suffers from schizophrenia.
Aug. 3, 2010: Omar Thornton shot 10 people, eight of them fatally, within three minutes at the Hartford Distributors warehouse in Manchester, Conn., before killing himself in what was the worst mass shooting in Connecticut before Friday's school shootings in Newtown.
Nov. 5, 2009: Thirteen soldiers and civilians were killed and more than two dozen wounded when a gunman walked into the Soldier Readiness Processing Center at Fort Hood, Texas, and opened fire. Army psychiatrist Maj. Nidal Hasan has been charged with 13 counts of premeditated murder and 32 counts of attempted premeditated murder.
April 3, 2009: A 41-year-old man opened fire at an immigrant community center in Binghamton, N.Y., killing 11 immigrants and two workers. Jiverly Wong, a Vietnamese immigrant and a former student at the center, killed himself as police rushed to the scene.
Feb. 14, 2008: Former student Steven Kazmierczak, 27, opened fire in a lecture hall at Northern Illinois University in DeKalb, Ill., fatally shooting five students and wounding 18 others before committing suicide.
April 16, 2007: Seung-Hui Cho, 23, kills 32 people and himself on Virginia Tech campus in Blacksburg, Va.
Oct. 2, 2006: Charles Carl Roberts IV, 32, shot to death five girls at West Nickel Mines Amish School in Pennsylvania, then killed himself.
March 21, 2005: Jeffrey Weise, 16, shot and killed five schoolmates, a teacher and an unarmed guard at a high school on the Red Lake Indian Reservation in Minnesota before taking his own life. Weise had earlier killed his grandfather and his grandfather's companion.
Oct. 28, 2002: Robert Flores Jr., 41, who was flunking out of the University of Arizona nursing school, shot and killed three of his professors before killing himself.
Sept. 27, 2001: A 57-year-old Swiss man armed with weapons including a SIG-Sauer pistol and an assault rifle killed 14 people in a cantonal parliament building in the Swiss city of Zug. Friedrich Leibacher killed himself following the shootings, which also wounded 18 others. Leibacher had been angry over perceived mistreatment by government officials.
March 5, 2001: Charles Andy Williams, 15, killed two fellow students and wounded 13 others at Santana High School in Santee, Calif.
April 20, 1999: Students Eric Harris, 18, and Dylan Klebold, 17, opened fire at Columbine High School in Littleton, Colo., killing 12 classmates and a teacher and wounding 26 others before killing themselves in the school's library.
May 21, 1998: Two teenagers were killed and more than 20 people hurt when Kip Kinkel, 17, opened fire at a high school in Springfield, Ore., after killing his parents.
March 24, 1998: Andrew Golden, 11, and Mitchell Johnson, 13, killed four girls and a teacher at a Jonesboro, Ark., middle school. Ten others were wounded in the shooting.
Dec. 1, 1997: Three students were killed and five wounded at a high school in West Paducah, Ky. Michael Carneal, then 14, later pleaded guilty but mentally ill to murder and is serving life in prison.
Oct. 1, 1997: Luke Woodham, 16, of Pearl, Miss., fatally shot two students and wounded seven others after stabbing his mother to death. He was sentenced the following year to three life sentences.
April 28, 1996: Martin Bryant, 29, bursts into cafeteria in seaside resort of Port Arthur in Tasmania, Australia, shooting 20 people to death. Driving away, he kills 15 others. He was captured and imprisoned.
March 13, 1996: Thomas Hamilton, 43, kills 16 kindergarten children and their teacher in elementary school in Dunblane, Scotland, and then kills himself.
Oct. 16, 1991: A deadly shooting rampage took place in Killeen, Texas, as George Hennard opened fire at a Luby's Cafeteria, killing 23 people before taking his own life. Twenty others were wounded in the attack.
July 18, 1984: James Oliver Huberty, an out-of-work security guard, kills 21 people in a McDonald's restaurant in San Ysidro, Calif. A police sharpshooter kills Huberty.
Sept. 25, 1982:
George Banks murders 13 people, including five of his own children, during a daylong shooting rampage in Wilkes-Barre and Jenkins Township.
Aug. 1, 1966: Charles Whitman opened fire from the clock tower at the University of Texas at Austin, killing 16 people and wounding 31.