Authorities in western Wyoming searched Jackson Hole Middle School for explosive devices Wednesday morning after a bomb threat was received overnight.

Classes at the school started two hours later than usual due to the threat, which was received by Teton County School District staff.

According to a statement from the district, over 25 officers and other personnel from the Jackson Police Department, Teton County Sheriff's Office, Teton County Bomb Squad, Lander Police Department/K-9 bomb unit, the school district and the National Park Service.

Authorities, including a K-9 unit, swept the school and student backpacks. Officers found no explosive devices, and classes resumed shortly after 11:15 a.m.

The school was deemed safe for normal activities.

The district says an active law enforcement investigation into the threat is underway.