In a statement on Cwmcarn High School's website, headteacher Jacqui Peplinski said "concerns were dealt with swiftly".
"There was no risk to any staff or learner and the relevant support services were contacted as a precautionary measure."
"Cwmcarn High is a caring and safe environment and we are committed to everyone’s safety."
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Outbreaks of light rain or drizzle expected around the coast and hills.
Mike and Cynthia from Ystradgynlais flew out to the German city for a weekend away.
Fine and dry at first but becoming largely cloudy with outbreaks of rain or drizzle.