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."
More top news
Generally cloudy with fairly persistent rain through this evening, but the cloud and rain will break up overnight with drier conditions.
Wales fans are continuing to celebrate yesterday's historic Euro 2016 win over Northern Ireland, which sees them make the quarter finals.
A lot has happened in the days since the Brexit result. We've been asking people how they're feeling about the fallout of the referendum.