Markethill High School has confirmed four positive cases of Covid-19 and says all who have been in close contact with those affected have been notified.
Three of the cases involve students, two from the same family confirmed on Thursday, and a third positive result by another pupil on Saturday.
The fourth case affects someone “within the non-teaching staff”, who has not been on the school site since September 29.
Principal Colin Berry said there had been “much change and upheaval” to school life since Thursday.
He also confirmed that none of the pupils involved travel to the school by bus.
In an update via social media, Mr Berry reported: “All students identified as ‘close contacts’ have now been contacted directly by school. If your child has not been instructed to remain at home, they should return to school tomorrow.
“We must stress the importance of you notifying school should your child develop symptoms and if they are being tested.
“Students must not be sent to school if they are symptomatic or if someone in your household is being tested. It is essential that the school is informed of the result whether it is positive or negative. A test result should not be shared on social media without school being informed first.
“Students who have been instructed to self-isolate must remain at home and should not be out socialising.
“We know this is a critical time, particularly for our senior students but staff are working very hard behind the scenes to ensure learning continues online.
“We do not want to overwhelm our students so we recommend that they follow their daily timetable and the allotted times for each subject.
Many thanks for your continued patience and support.”
Join Our WhatsApp
Don't miss a headline with a daily round-up as well as major breaking news. Message 'News' to 07938050001.