Mass shootings in U.S. history

POSTED: 7:20 AM PDT July 20, 2012    UPDATED: 5:39 AM PDT April 3, 2014 
Fort Hood

A gunman opened fire at the Fort Hood military post in Texas on Wednesday, killing three people and wounding 16 before committing suicide. Take a look at some of the worst mass shootings in U.S. history.