So, when is the right time to talk about guns?
April 1999 - two teenage schoolboys shot and killed 12 schoolmates and a teacher at Columbine High School in Littleton, Colorado, before killing themselves.
4976 days since that we haven't talked about gun violence.
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July 1999 - a stock exchange trader in Atlanta, Georgia, killed 12 people including his wife and two children before taking his own life.
4884 days since that we haven't talked about gun violence.
September 1999 - a gunman opened fire at a prayer service in Fort Worth, Texas, killing six people before committing suicide.
4823 days since that we haven't talked about gun violence.
October 2002 - a series of sniper-style shootings occurred in Washington DC, leaving 10 dead.
3696 days since that we haven't talked about gun violence.
August 2003 - in Chicago, a laid-off worker shot and killed six of his former workmates.
3392 days since that we haven't talked about gun violence.
November 2004 - in Birchwood, Wisconsin, a hunter killed six other hunters and wounded two others after an argument with them.
2935 days since that we haven't talked about gun violence.
March 2005 - a man opened fire at a church service in Brookfield, Wisconsin, killing seven people.
2814 days since that we haven't talked about gun violence.
October 2006 - a truck driver killed five schoolgirls and seriously wounded six others in a school in Nickel Mines, Pennsylvania before taking his own life.
2235 days since that we haven't talked about gun violence.
April 2007 - student Seung-Hui Cho shot and killed 32 people and wounded 15 others at Virginia Tech in Blacksburg, Virginia, before shooting himself, making it the deadliest mass shooting in the United States after 2000.
2054 days since that we haven't talked about gun violence.
August 2007 - Three Delaware State University students were shot and killed in “execution style” by a 28-year-old and two 15-year-old boys. A fourth student was shot and stabbed.
1931 days since that we haven't talked about gun violence.
September 2007 - A freshman student at Delaware State University shot and wounded two other students at a campus dining hall.
1901 days since that we haven't talked about gun violence.
December 2007 - a 20-year-old man killed nine people and injured five others in a shopping center in Omaha, Nebraska.
1809 days since that we haven't talked about gun violence.
December 2007 - a woman and her boyfriend shot dead six members of her family on Christmas Eve in Carnation, Washington.
1809 days since that we haven't talked about gun violence.
February 2008 - a shooter who is still at large tied up and shot six women at a suburban clothing store in Chicago, leaving five of them dead and the remaining one injured.
1749 days since that we haven't talked about gun violence.
February 2008 - a man opened fire in a lecture hall at Northern Illinois University in DeKalb, Illinois, killing five students and wounding 16 others before laying down his weapon and surrendering.
1749 days since that we haven't talked about gun violence.
July 2008 – A former student shot three people in a computer lab at South Mountain Community College, Phoenix, Arizona.
1596 days since that we haven't talked about gun violence.
September 2008 - a mentally ill man who was released from jail one month earlier shot eight people in Alger, Washington, leaving six of them dead and the rest two wounded.
1535 days since that we haven't talked about gun violence.
October 2008 - Several men in a car drove up to a dormitory at the University of Central Arkansas and opened fire, killing two students and injuring a third person.
1504 days since that we haven't talked about gun violence.
December 2008 - a man dressed in a Santa Claus suit opened fire at a family Christmas party in Covina, California, then set fire on the house and killed himself. Police later found nine people dead in the debris of the house.
1443 days since that we haven't talked about gun violence.
March 2009 - a 28-year-old laid-off worker opened fire while driving a car through several towns in Alabama, killing 10 people.
1353 days since that we haven't talked about gun violence.
March 2009 - a heavily-armed gunman shot dead eight people, many of them elderly and sick people, in a private-owned nursing home in North Carolina.
1353 days since that we haven't talked about gun violence.
March 2009 - six people were shot dead in a high-grade apartment building in Santa Clara, California.
1353 days since that we haven't talked about gun violence.
April 2009 – An 18-year-old former student followed a pizza deliveryman into his old dormitory, and shot the deliveryman, a dorm monitor, and himself at Hampton University, Virginia.
1323 days since that we haven't talked about gun violence.
April 2009 - a man shot dead 13 people at a civic center in Binghamton, New York.
1323 days since that we haven't talked about gun violence.
July 2009 - Six people, including one student, were shot in a drive-by shooting at a community rally on the campus of Texas Southern University, Houston.
1231 days since that we haven't talked about gun violence.
November 2009 - U.S. army psychologist Major Nidal Hasan opened fire at a military base in Fort Hood, Texas, leaving 13 dead and 42 others wounded.
1109 days since that we haven't talked about gun violence.
February 2010 – A professor opened fire 50 minutes into at a Biological Sciences Department faculty meeting at the University of Alabama, killing three colleagues and wounding three others
1019 days since that we haven't talked about gun violence.
January 2011 - a gunman opened fire at a public gathering outside a grocery in Tuscon, Arizona, killing six people including a nine-year-old girl and wounding at least 12 others. Congresswoman Gabrielle Giffords was severely injured with a gunshot to the head.
682 days since that we haven't talked about gun violence.
July 2012 - Masked gunman opens fire at midnight cinema screen of new Batman film The Dark Knight Rises, killing 12 and injuring 58. Suspect James Holmes is arrested by oplice and awaiting trial.
135 days since that we haven't talked about gun violence.
August 2012 - Gunman kills six people at SIkh temple in Wisconsin before being shot dead by police. Suspect is named as white supremacists Wade Michael Page.
104 days since that we haven't talked about gun violence.
December 2012 - Gunman kills ????
0 days since that we haven't talked about gun violence.
*Note, I started dates from the first day of the month after these shootings, except for today's tragedy, as the article didn't use precise dates.