Harvard School District 50 officials found the student who has been leaving bullet shell casings on school property and a bus, the Northwest Herald reports.
Students were kept in their classrooms Wednesday at all five schools when more shell casings were found. It was the second time this week Harvard Police had to search the schools, the Herald reports.
District 50 staff members determined a student brought the shell casings to the school, according to a district email. The student has not been identified, the story stated.
Maintenance staff at Crosby Elementary School on Monday found a .22-caliber shell casing on the cafeteria floor. Administrators kept students in their classrooms for more than an hour while police searched the building.