File Photo | Harvard High School

Police say they are investigating after a photograph threatening violence at Harvard High School was sent to students’ phones on Wednesday.

The Harvard Police Department was notified around 1:23 p.m. Wednesday about a threat at Harvard High School, 1103 North Jefferson Street in Harvard.

Harvard Deputy Police Chief Tyson Bauman said an unknown person or persons used Apple AirDrop to send a photograph to the phones of students at the school.

The photograph conveyed a threat that violence would occur on Thursday at the school, Bauman said.

The police department is working in conjunction with Harvard Community Unit School District 50 officials.

The Harvard Police Department is actively investigating the origin of the threat and attempting to identify the person or person who sent it, Bauman said.

There will be an increased police presence before, during and after school hours.

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Anyone with information is asked to contact the Harvard Police Department at 815-943-4431.