Star Valley High School in Afton, Wyoming was placed under a precautionary lockdown Monday morning.
The Lincoln County School District #2 said the lockdown was instituted for purposes of student safety under the direction of law enforcement. Police were active at all district buildings as a precaution.
No specific threat was validated. In a short statement, the district said it had been deemed safe for students to return to normal schedule.
Law enforcement said it would continue to monitor the situation.