Beginning last weekl, the threatening comments sparked rumors and fear among students, prompting an investigation by school administrators and the Alexandria Police Department.
No charges have been filed. The school system takes threats seriously.
The principal said four students were involved.
Tuesday will be the 11-year anniversary of the shooting at Columbine High School near Littleton, Colo. Two students went on a shooting spree, killing 12 other students and a teacher and injuring 21 others.