Aug 1, 1966: Charles Whitman, 25, a student and former Marine, killed his wife and mother before carrying a rifle to the tower on the campus of the University of Texas in Austin. In a 96-minute rampage he fatally shot 14 others before police shot and killed him.
July 12, 1976: Edward Charles Allaway, 37, a custodian at California State University Fullerton killed seven people in the library with a gun purchased at Kmart. He was found not guilty by reason of
Jan. 17, 1989: Patrick Edward Purdy, a 24-year-old drifter, opened fire with a semi-automatic rifle in Stockton, California playground, killing five children and wounding one teacher and 29 other children. He killed himself.
Dec 1, 1997: 14-year-old Michael Carneal fires on students attending a prayer circle at a school in West Paducah, Kentucky. He kills three students and wounds five.
March 24, 1998: Mitchell Johnson, 13, and Andrew Golden, 11, pulled a fire alarm and began shooting as everyone exited a school in Jonesboro, Arkansas, killing four students and one teacher and injuring nine others.
April 20, 1999: Eric Harris, 18, and Dylan Klebold, 17, walked into Columbine High School in Colorado and in a rampage of gunfire and homemade bombs killed 12 students and a teacher and then themselves.
March 21, 2005: Jeffrey Weise, 17, went on a shooting spree at Red Lake High School on the Red Lake Indian Reservation in Minnesota. He killed nine people, including his grandfather, and wounded five others before killing himself.
Oct 2, 2006: Charles Carl Roberts IV, 32, a milk-van driver, killed five girls ages 7 to 13 execution-style, then turned the gun on himself, in a one-room Amish schoolhouse in Nickel Mines, Pennsylvania.
April 16, 2007: Seung-Hui Cho, 23, a student at Virginia Tech University in Blacksburg, Virginia., shot and killed 32 people in attacks two hours apart in two campus buildings. Cho, who was diagnosed with mental illness, killed himself.
April 2, 2012: One L Goh, 43, a former nursing student at private Oikos University in California, sprayed gunfire around a classroom, killing seven people.

December 14, 2012: Adam Lanza, 20, killed 20 children and six adults at the school. Lanza also was found dead at the scene, authorities said. The body of a woman believed to be his mother was found at their home in Newton, authorities said.