Authorities say a Scottsbluff high-schooler brought a semiautomatic gun to school last month by accident and had no plans to use it.

Scottsbluff police have cited the 17-year-old for possession of a firearm on school grounds and possession of a firearm by a minor. Scottsbluff High School officials have expelled him for one year.

School officials have said two students found the unloaded gun in a boys' bathroom on April 28. There was no note with it, and there was no known threats against any students.

Police Captain Kevin Spencer said investigators are trying to determine how the student got possession of the gun, which was taken during a burglary several years ago in Denver.