Marshall Middle School was evacuated Tuesday afternoon after a gas odor was reported inside the building, authorities said.
The fire department was called shortly before 3:30 p.m., a Sedgwick County emergency dispatch supervisor said. The school was evacuated as a precaution.
Students were dismissed for the day from their evacuation location across the street, district spokeswoman Susan Arensman said.
Fire officials and Kansas Gas Service investigated the source of the odor and gave an all-clear after about an hour. Staff were allowed to return to the building.
The cause of the odor has not been released.