The all-clear has been given at John Overton High School in Nashville after a gas odor prompted an evacuation.
The call came in around 6:30 a.m. Wednesday at the school located off Franklin Pike.
Officials said the smell orginated from hydrogen sulfide, a sewer gas.
Students were briefly taken outside before being moved into the cafeteria and gym.
Metro Schools tweeted that the following busses are running late because of the issue: Norman Binkley ES, Crieve Hall ES, Haywood ES, Tusculum ES, Granbery ES, Shayne ES, Croft MS, McMurray MS, and Oliver MS.
The Overton Cluster buses picked up elementary and middle school students. High school students were still in school until officials give officials additional information.