— 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.
— 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. 20 others were wounded in the attack.
— June 18, 1990: James Edward Pough shoots people at random in a General Motors Acceptance Corp. office in Jacksonville, Fla., killing 10 and wounding four, before killing himself.
— Dec. 6, 1989: Marc Lepine, 25, bursts into Montreal's Ecole Polytechnique college, shooting at women he encounters, killing nine and then himself.
— Aug. 19, 1987: Michael Ryan, 27, kills 16 people in small market town of Hungerford, England, and then shoots himself dead after being cornered by police.
— July 12, 1976: Edward Charles Allaway, a custodian in the library of California State University, Fullerton, fatally shot seven fellow employees and wounded two others.
— Aug. 20, 1986: Pat Sherrill, 44, a postal worker who was about to be fired, shoots 14 people at a post office in Edmond, Okla. He then kills himself.
— 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.
— Aug. 1, 1966: Charles Whitman opened fire from the clock tower at the University of Texas at Austin, killing 16 people and wounding 31.
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