The Afton Superintendent, Elizabeth Briggs, says threats have been made every Thursday for the last 3 weeks, including this Thursday.
The bomb threats were found written in bathrooms.
Each time K-12 students were evacuated and state police searched the building.
Last Thursday, students were outside for 3 hours following a message that mentioned a specific time.
Brigg's says it is the first time since 2001 threats have been made at the school.
After Thursday's incident, Afton police arrested 16 year old Philip Sergent of Afton.
He's charged with a falsely reporting an incident, a felony.
School administrators will also discuss whether to take disciplinary action.