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The massacre at Columbine High School is, to this day, the deadliest high school shooting in American history. 13 people were killed and 21 were wounded.
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Seven people were killed in this racially-motived shooting at the hands of a Lockheed Martin employee named Doug Michaels. Most victims were African American.
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The massacre at Virginia Tech is, to this day, the single deadliest [school shooting](http://www.nytimes.com/glogin?URI=http://www.nytimes.com/2007/04/16/us/16cnd-shooting.html&OQ=pagewantedQ3DallQ26_rQ3D0&OP=a5c44492Q2FHyJZH7AZHdddHbZgIHQ27yae,yyZ-H-UUQ60HUWH6Q3EHKeH6Q3Ea7Q27Q7EebyyZQ207F(bZgI) in history. The gunman shot 56 people and wound up killing 33 total.
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A gunman named James Holmes entered the premiere of "The Dark Knight Rises" at the Century 16 movie theater and killed 12 people.
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Adam Lanza took a Bushmaster AR-15 assault rifle and entered a local elementary school, taking the lives of 27 people in the process. 20 of the victims were children ages 7 or under.
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The mass shooting at a navy yard in the nation's capital left 12 people dead and 3 people injured.
