A 17-year-old was arrested and another has agreed to turn himself in after threats of violence were discovered Tuesday against the Tioga Independent School District.

“I have no way of knowing if they were credible or not,” Tioga Police Chief Curtis Macomb said of the threats. “All I can tell you is that when somebody makes a threat, we take it seriously.”

Macomb said the threats were found online and alluded to a shooting in the school. Additional officers were placed on duty all day Wednesday, and a 17-year-old Tioga student was arrested on a terroristic threat charge — a third-degree felony offense. The student was booked into the Grayson County Jail, and a second arrest warrant was issued for another 17-year-old currently outside the state.

“One additional warrant has been issued for an individual that is currently in Oklahoma, but I’ve been in communication with him, and he has agreed to turn himself in — in the next couple of days,” Macomb said Thursday evening.

Macomb said the second suspect is not currently enrolled at Tioga ISD, but he was a former student. Macomb said that student is enrolled in some type of alternative school.