MOUNT VERNON, OH (WCMH) — A social media threat targeting a Knox County school ended with one student in police custody.

The Mount Vernon City School District released a letter to parents Tuesday explaining the threat found on Snapchat.

Superintendent William Seder Jr. said the threat was published Monday night. As soon as they found it, they notified police. Seder said the student was arrested about 20 minutes later.

The student has not been identified by the school, but police believe nobody else was involved.

The school said they increased security Tuesday morning, but classes went as scheduled.