284 pupils at Royal Wootton Bassett Academy have been sent home to self-isolate.
It comes after a Year 9 student tested positive for coronavirus, taking the total number of schoolgoers home from school in the Wiltshire Council authority area to 650.
Headteacher Anita Ellis said the school has taken all precautionary measures since receiving news for the COVID-19 case, with “bubble” measures being followed to minimise the risk.
The pupils will remain in self-isolation for 14 days and are being asked to take lessons from home.