No explosive gas found at the Southern Boone High School last (Monday) night after a student reported a smell.
Fire officials in Ashland went to the school around 8:30 and evacuated the building.
The crews report that gas level readings did not detect any explosive gas.
The odor is said to have possibly been Mercaptan, which is a chemical added to natural gas to give it some odor which came from an outside source.
The school district is said to be working with Ameren on the issue.