April 1999 – Two heavily armed teenagers go on a rampage at Columbine High School in Littleton, Colorado, shooting 13 students and staff before taking their own lives.

July 1999 – A gunman kills nine people at two brokerages in Atlanta, after apparently killing his wife and two children. He commits suicide five hours later.

October 2002 – Two men kill at least 10 people in a string of sniper-style shootings that terrorize the Washington, D.C., area.

Nov. 21, 2004 – Six people are killed when a man shoots eight people while deer hunting in northern Wisconsin.

March 12, 2005 – A man opens fire at a Living Church of God service at the Sheraton Hotel in Brookfield, Wisconsin, killing seven and wounding four. He then commits suicide.

April 16, 2007 – A gunman kills 32 people and himself at Virginia Tech, a university in Blacksburg, Virginia.

Oct. 7, 2007 – A sheriff’s deputy kills six people and wounds one at his ex-girlfriend’s apartment, in Crandon, Wisconsin. He then kills himself.

April 3, 2009 – A Vietnamese immigrant opens fire at an immigrant services center in Binghamton, New York, killing 13 people. He then kills himself.

Nov. 5, 2009 – A gunman opens fire at Fort Hood, a U.S. Army base in Texas, killing 13 people and wounding 32. An Army major is charged in connection with the rampage.

Jan. 8, 2011 – Then-U.S. Congresswomen Gabrielle Giffords is the target of an assassination attempt in Tucson, Arizona, in which six people are killed and 13, including Giffords, are wounded.

April 2, 2012 – A gunman kills seven people and wounds three in a shooting at a Christian college in Oakland, California.

July 20, 2012 – A masked gunman kills 12 people and wounds 58 when he opens fire on moviegoers at a showing of the Batman film “The Dark Knight Rises” in Aurora, a suburb of Denver. A 24-year-old former university student is charged in connection with the rampage.

Aug. 5, 2012 – A gunman kills six people during Sunday services at a Sikh temple in Oak Creek, Wisconsin, before he is shot dead by police.

Dec. 11, 2012 – A gunman opens fire inside an Oregon shopping mall, killing two people and wounding one. He then kills himself.

Dec. 14, 2012 – A heavily armed gunman kills 20 children and six adults at an elementary school in Newtown, Connecticut. Before the rampage, the 20-year-old shooter first shot and killed his mother in their home. When authorities approached the school, the shooter turned the gun on himself.

Sept. 16, 2013 – A 34-year-old man opens fire at the U.S. Navy Yard in Washington, not far from the U.S. Capitol and the White House, in an incident in which 13 people, including the gunman, are killed. (Reporting By Patrick Rucker; Editing by David Brunnstrom) DM

Photo: Street artist Mark Panzarino, 41, prepares a memorial as he writes the names of the Sandy Hook Elementary School victims during the six-month anniversary of the massacre, at Union Square in New York, June 14, 2013. Six months after a gunman killed 26 children and adults at the elementary school, families and local officials marked the day by honoring the victims and renewing the fight for stricter gun control. REUTERS/Eduardo Munoz