1. Top 7 worst U.S. school shootings GRAYSON DOWDY

2. Gunman Patrick Purdy, seen in this police photo, date unknown, opened fire with an AK 47 assault rifle on the playground of Cleveland Elementry School in Stockton, Calif., on Jan. 17, 1989. Five school children were killed and 30 others injured before Purdy took his own life. Photo: Ho, Associated Press

3. In a May 4, 1970 file photo, a group of youths cluster around a wounded person as Ohio National Guardsmen, wearing gas masks, hold their weapons in the background, on Kent State University campus in Kent, Ohio. Members of the Guards killed four students and injured nine during a campus protest against the Vietnam War. Photo: Douglas Moore, Associated Press.

4. In this April 20, 1999 file photo Eric Harris, left, and Dylan Klebold, carrying a TEC-9 semi- automatic pistol, are seen in a photo made from a security camera image in the cafeteria at Columbine High School, in Littleton, Colo., during their shooting rampage which killed a teacher and 12 students. Photo: Anonymous, ASSOCIATED PRESS.

5. This 2005 class photo shows Jeff Weise, who went on a shooting rampage at Red Lake Senior High School 21 March, 2005, on the Red Lake Indian Reservation in Minnesota. Weise, a student at the school, killed five students, a teacher, Brun, his grandfather and his companion before turning the gun on himself.

6. Charles Carl Roberts, a 32-year-old diary truck driver, whom police identified as the gunman who killed three schoolgirls execution style and then shot himself dead in a schoolhouse in Nickel Mines, Pennsylvania, is seen in this police handout released October 2, 2006. Photo: Pennsylvania State Police, Reuters

7. An image that NBC News say they received from Cho Seung-Hui, the shooter in the Virginia Tech shootings, is seen as it is aired on the NBC Nightly News, April 18, 2007. The gunman who went on a deadly rampage at Virginia Tech university paused between shootings to mail a rambling account of grievances, photos and videos to NBC, the network said.

8. In this Tuesday, Feb. 28, 2012 photo, seventeen-year-old T.J. Lane is led from Juvenile Court by Sheriff's deputies in Chardon, Ohio, after his arraignment in the shooting of five high school students Monday. Three of the five students wounded in the attacks have since died. Photo: Mark Duncan, Associated Press