Clarification: An earlier version of this timeline omitted several significant shootings that have taken place at colleges and other schools since the 1960s.
Feb. 14, 2008: A 27-year-old man goes on a rampage at Northern Illinois University in DeKalb, shooting 21 people, killing five and later himself. University police report that the suspect, a former student, had stopped taking medication and had been acting "somewhat erratic."
Feb. 12, 2008: In Oxnard, Calif., a 14-year-old shoots a 15-year-old classmate, who later dies of his injuries. Law enforcement cites "bad blood" between the teens.
Feb. 11, 2008: In Memphis, a 19-year-old senior is shot in his school's gym by a 17-year-old sophomore, following a feud that started off campus earlier in the week; after the shooting, the suspect hands his gun to a coach, saying, "It's over now."
Feb. 8, 2008: A nursing student shoots two women and then herself in a classroom at Louisiana Technical College, outside Baton Rouge.
Feb. 7, 2008: In Portsmouth, Ohio, a small community near the Kentucky border, a man shoots his estranged wife at the Notre Dame Elementary School.
Feb. 4, 2008: In Memphis's Hamilton High School, a 16-year-old student is shot in the leg during an argument with another student over music.
Jan. 16, 2008: As students are being dismissed early from school, one is wounded in the shoulder after being shot in the parking lot of Crossroads Charter High School in Charlotte, N.C.
Dec. 13, 2007: Two doctoral students from India are shot and killed in student apartments on the Louisiana State University campus.
Dec. 12, 2007: After taking his father's pistol to school, a student shoots a 14-year-old classmate at a private school outside New Delhi; gun violence is very rare in India.
Dec. 10, 2007: A 24-year-old goes on a shooting spree at a megachurch in Colorado Springs and a Denver-area missionary training school, killing four and wounding four others; the gunman, who law enforcement sources said "hated Christians," kills himself.
Nov. 7, 2007: An 18-year-old man, a former student, shoots seven people and wounds 11 others before taking his own life at a high school in southern Finland; this is the first known school shooting in Finland, where gun ownership is fairly common by European standards but shootings are rare.
Oct. 24, 2007: In Saginaw, Mich., four South Middle School students are shot by a high school student at a middle school football game; the victims' injuries are not life threatening.
Oct. 10, 2007: A 14-year-old gunman opens fire at Success Tech Academy, a nontraditional high school in Cleveland, wounding two students and two teachers before killing himself.
Sept. 30, 2007: A University of Memphis football player dies after being shot and then crashing his car into a tree, following a botched robbery attempt outside a university housing complex.
Sept. 21, 2007: Two Delaware State University students are shot and wounded at the Campus Mall while returning from an on-campus cafe.
Aug. 5, 2007: Four young people are shot in the head at close range, three fatally, in the parking lot of the K-8 Mount Vernon School in Newark, N.J.; all of the victims had been planning to attend Delaware State in the fall.
April 16, 2007: Before killing himself, a 23-year-old Virginia Tech student, Seung Hui Cho, kills two students in a dorm; then two hours later across campus in Norris Hall, he kills 25 more students and five faculty members. Fifteen others are wounded in the deadliest campus shooting in U.S. history.
April 2, 2007: A program coordinator for the University of Washington's College of Architecture is shot and killed by a man in an apparent murder-suicide.
Oct. 2, 2006: A gunman kills six people, including himself, and wounds more at a one-room Amish schoolhouse in Lancaster County, Pa.
Sept. 29, 2006: A 15-year-old student brings two guns to Weston Schools in rural Cazenovia, Wis., and fatally shoots his principal after the principal had given him a disciplinary warning for having tobacco on school grounds.