On May 2, 1967, The Black Panthers walked into the California State Capitol fully armed to protest a bill to limit gun possession. Ronald Reagan signed the bill into law.
January 8, 2011. Former Rep. Gabby Giffords (D-AZ) was shot in the head when Jared Loughner opened fire on an event she was holding at a Safeway market in Tucson, AZ. Six people died.
April 3, 2009. Jiverly Wong opened fire at an immigration center in Binghamton, New York before committing suicide. He killed 13 people and wounded 4.
April 20, 1999. In the deadliest high school shooting in US history, teenagers Eric Harris and Dylan Kiebold shot up Columbine High School in Littleton, CO. They killed 13 people and wounded 21.