A gunman at a Connecticut elementary school killed 27 people, including 18 children on Friday. It is among the world's worst mass shootings. Here is a look at some others:
• Feb. 28, 2012: T.J. Lane, 17, enters the cafeteria at Chardon High School in northeastern Ohio and shoots five students, killing three.
• Sept. 23, 2008: Matti Saari, 22, walks into a vocational college in Kauhajoki, Finland, and opens fire, killing 10 people and burning their bodies with firebombs before shooting himself fatally in the head.
• April 16, 2007: Seung-Hui Cho, 23, kills 32 people and himself on Virginia Tech campus in Blacksburg, Va.
• April 26, 2002: Robert Steinhaeuser, 19, who had been expelled from school in Erfurt, Germany, kills 13 teachers, two former classmates and policeman, before committing suicide.
• 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.
• March 13, 1996: Thomas Hamilton, 43, kills 16 kindergarten children and their teacher in elementary school in Dunblane, Scotland, and then kills himself.
• Dec. 6, 1989: Marc Lepine, 25, bursts into Montreal's Ecole Polytechnique college, shooting at women he encounters, killing nine and then himself.