With today's deadly school shooting in Nevada, look back at other major school shootings in U.S. history.
A student and a teacher were killed in a shooting at a middle school in Sparks, Nev., on Monday. A 13-year-old student told the Reno Gazette Journal the teacher was shot after the student pointed a gun at the teacher, and the teacher told the student to put it down. Here's a look back at major school shootings in U.S. history:
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