WOONSOCKET, R.I. (AP) — Woonsocket police have arrested four students in connection with a recent string of bomb threats at Woonsocket High School.

Police say 18-year-old Khalil Oliver and three juveniles are facing one count each of making a bomb threat and conspiracy. The juveniles are a 16-year-old boy and 15-year-old and 14-year-old girls. More arrests are expected.

Police evacuated the school and searched the building after each of the four bomb threats but found no danger. The Woonsocket Call reported authorities said the threats were pranks meant to disrupt classes but that the public safety response was costly. Detective Jamie Paone said one day cost over $100,000 when the state bomb squad was called in.

Police said they identified the students through tips from other students.

A message was left for Paone.

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