The 50 deaths, so far, are 18 more than the 32 people a gunman killed in the second most-fatal massacre, at Virginia Tech in 2007, according to data from Mother Jones that goes back to 1982.
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The third-deadliest shooting was at the Newtown elementary school in Connecticut in 2012 when 22 first-graders and six adult school staff members were killed. The fourth highest death toll was in San Bernardino in December when 14 were killed.
Next on the list of deadliest shootings is the 1999 tragedy at Columbine High School in Littleton, Colorado, when 13 people were killed by two fellow students. Near Littleton, at a movie theater in Aurora, Colorado, another shooting massacre occurred in 2012, killing 12.
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