CLAYTON, Mo. - A fog machine caused the evacuation of a Clayton middle school Thursday.

Around 3 p.m. students and staff were evacuated from Wydown Middle School after smoke appeared throughout the building.

Firefighters with the Clayton Fire Department were able to quickly determine the source of the smoke was a malfunctioning fog/smoke machine set up for Thursday night's Give Back Night.

Students were allowed to return to their classrooms before they were dismissed.

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