Environmental health officers from Pembrokeshire County Council are investigating an outbreak of sickness and diarrhoea at Goodwick primary school in Fishguard.
A hundred and seventeen pupils out of a hundred and twenty six failed to turn up for class today.
Thirteen staff are also absent.
Parents have been told to keep their children home until they're clear of symptoms for 48 hours.
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A band of rain pushing in overnight, bringing with it the odd spot of coastal and hill fog, but things should improve by tomorrow.
Local authorities said the move is necessary to "avert the growing number of deaths and increasing harm linked to psychoactive substances".
Sunny and bright spells for most of us this afternoon, feeling pleasantly warm.