The boarding school, which counts Prince Harry and Boris Johnson among its alumni, sent a letter to parents detailing the outbreak today, the Mail Online reports.
Headmaster Simon Henderson said in the letter: ‘Having been largely Covid free since Long Leave, a number of symptomatic boys and staff have tested positive in the past few days. We are awaiting results on several others, with more scheduled to be tested.
‘We also now have a significant number of boys and staff self-isolating as close contacts.’
Mr Henderson went on to say the school had taken medical advice, which suggested there was a ‘danger’ of cases increasing if staff did not take immediate action.
He also stated that he wished to avoid pupils and staff having to self-isolate over the Christmas holidays. He did not specify in the letter which age group had been affected by the outbreak.
Pupils at the school will now work remotely until the end of term, while the physical building closes down. However, houses will remain open over the weekend and into the weekend to give parents enough time to pick up their children.
End of term exams, known as Trials in the school, will also still take place, Mr Henderson added.
The world-famous school, which opened in 1441, has around 1,300 pupils who join when they are 13 and are each given their own study-bedroom. The school costs £42,500-a-year to attend.