Sept. 14: Two 17-year-olds are arrested at Green Bay East High School after another student told an associate principal of a suspected plot of a shooting spree at the school. The two boys had amassed guns, ammunition, bombs and other gear in their homes to use at the school, police say.

On Friday, one of the teens, William Cornell, 17, was ordered Friday to stand trial by Brown County Court Commissioner John Burdick.

April 28: A Dodgeville teacher notices a 15-year-old student carrying a gun. The student was also carrying a knife. A subsequent locker search turns up an air pistol in another student's locker.

April 27: A DeForest student is arrested after police find two loaded guns in his car at school.

Feb. 21: A 17-year-old girl shoots a 14-year-old girl at a Madison Memorial school bus stop 20 times with a pellet gun.

Nov. 16, 2005: A 13-year-old Blackhawk Middle School student is arrested after he shot three of his peers with a BB gun during a morning bus ride to school.

Oct. 20, 2005: A 17-year-old male Memorial High School freshman is arrested for allegedly having a loaded 9 mm handgun in the school parking lot.

March 22, 2005: A 16-year-old brings a sawed-off shotgun to Case High School in Racine County's Mount Pleasant.

Nov. 21, 2003: A 13-year-old boy allegedly brings a gun and a loaded magazine to West De Pere Middle School after taking it from the top of his father's gun cabinet.

Nov. 15, 1998: Five teens are arrested after police learn of their plot to kill educators and up to 20 students at Burlington High School. The five boys described their plot as a suicide mission.

Oct. 7, 1998: A 13-year-old Jefferson Middle School student in Madison threatens other students with a BB gun.

April 13, 1998: Michael T. Lareau, 16, of Wyocena, shoots custodian Ralph Pulver at Pardeeville Elementary School. Lareau shot Pulver through a door and wounded him in the eye as the custodian was leaving work. Lareau was hoping to steal Pulver's car with three other teens. Lareau was sentenced to 40 years in prison.

Feb. 18, 1997: A Madison West High School student aims a loaded semiautomatic handgun at another student after getting off the bus.

Dec. 14, 1995: Five Lindbergh Elementary students in Madison, ages 9 to 11, are found to be carrying guns around school, including a loaded .22-caliber revolver.

Oct. 11, 1995: A 14-year-old Toki Middle School student threatens to shoot school staff members with a BB gun he brought to school and attempts to stab the principal with a pen.

Nov. 19, 1969: A 14-year-old boy shoots and kills junior high school principal Martin Mogensen, 46, in the principal's office. After shooting four or five shots from a 20-guage shotgun, the student quietly waits in the school hall until police arrive.