An overheated motor on an HVAC unit caused smoke to fill the Little Theater and other nearby areas of Jefferson City High School on Monday afternoon.
According to fire department reports, the alarm came in around 12:09 p.m.
School maintenance crews had discovered the problem prior to the arrival of firefighters.
As precaution, students at the school were evacuated while fire crews cleared the smoke out of the building.
It took crews about 20 minutes to get the smoke out and allow students to re-enter the building.