Mass shootings in U.S. history

Published On: Jul 20 2012 07:20:30 AM PDT   Updated On: Mar 10 2014 12:13:18 PM PDT
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.