A primary school in Bangor is the first to close completely in Northern Ireland after two cases of coronavirus were identified, BBC News NI understands.
St Comgall’s Primary said the decision to shut for 14 days was approved “at a higher level”.
Principal Cathy Hunter said she had “no other option” but said there was “no need to panic”.
She added that pupils were not required to self-isolate, and it was hoped the school could reopen on 12 October.
In a message to parents, Mrs Hunter said the move was to “protect the health and safety of the whole school community” after a further case was identified within the school community.
“Please reassure your child that all is well,” she said.
“I sincerely apologise for the inconvenience caused but know that you will want to support this decision in order to return out school community safely as soon as we can.”
According to the most recent information available, St Comgall’s has 312 pupils.
A number of schools in NI have reported positive Covid-19 cases among staff or pupils since schools began to reopen on 24 August.
In the vast majority of cases, specific classes of pupils have been told to self-isolate following advice from the Public Health Agency.
A number of schools have closed for deep cleans after positive tests but only for a short period.
Last week, Holy Cross College in Strabane and Malone College in Belfast closed for a number of days after positive cases were reported.
Earlier in September, Fleming Fulton, a special school in Belfast, closed after two members of staff tested positive.