A timeline of some of the worst mass shootings in the country’s history.
July 20, 2012: At least 12 people were killed when a gunman entered an Aurora, Colo., movie theater, released a canister of gas, and then opened fire during the opening night of the Batman movie “The Dark Knight Rises.”
Nov. 5, 2009: Thirteen soldiers and civilians were killed and more than two dozen wounded when a gunman opened fire at Fort Hood, Texas. Army psychiatrist Major Nidal Hasan is charged with 13 counts of premeditated murder.
March 10, 2009: Michael McLendon, 28, killed 10 people — including his mother, four other relatives, and the wife and child of a local sheriff’s deputy — across two rural Alabama counties. He then killed himself.
April 16, 2007: Seung-Hui Cho, 23, killed 32 people and himself on the Virginia Tech campus in Blacksburg, Va.
April 20, 1999: Students Eric Harris, 18, and Dylan Klebold, 17, opened fire at Columbine High School in Littleton, Colo., killing 12 classmates and a teacher and wounding 26 others before killing themselves in the school’s library.
Oct. 16, 1991: George Hennard opened fire in Killeen, Texas, killing 23 people before taking his own life. Twenty others were wounded in the attack.
June 18, 1990: James Edward Pough shot people at random in a General Motors Acceptance Corp. office in Jacksonville, Fla., killing 10 and wounding four before killing himself.
Aug. 20, 1986: Pat Sherrill, 44, a postal worker who was about to be fired, shot 14 people at a post office in Edmond, Okla. He then killed himself.
July 18, 1984: James Oliver Huberty, an out-of-work security guard, killed 21 people in a McDonald’s restaurant in San Ysidro, Calif. A police sharpshooter killed Huberty.
July 12, 1976: Edward Charles Allaway, a custodian in the library of California State University, Fullerton, fatally shot seven fellow employees and wounded two others.
Aug. 1, 1966: Charles Whitman opened fire from the clock tower at the University of Texas at Austin, killing 16 people and wounding 31.
SOURCE: Associated Press