Missoula police officers tell NBC Montana that they’ve identified more than one student as persons of interest in threats found written in the boys bathroom at Big Sky High School last Monday. Officers tell NBC Montana that officers are working to compare the students’ handwriting to the writing in the threats.

Officers say the graffiti included threats to shoot one student and to bomb the school. Officers say the graffiti claimed the actions would happen on September 13, and officers say that while the day has come and gone, security remains tightened at the campus.