A head teacher has blamed staff for an outbreak of Covid-19 at his school after they attended a party.
Eight members of staff at Bacup Holy Trinity Stacksteads CE Primary School have contracted Covid-19 since the party on 5 September, John Aspin said.
Another three, who did not attend, have since been infected and the whole school has now had to close.
Staff "jeopardised hard work" to keep the school safe, Mr Aspin said.
In a letter to parents published on the school website, Mr Aspin said staff at the Lancashire school took an "ill-advised risk" when they attended a party at the home of a former colleague.
He said he had "spent many hours over the weekend" trying to work out why so many staff were becoming ill as he had not been told about the gathering.
"Had I been aware of the event I would have told them that they should not attend because of the risks, but sadly I was not informed", he said.
He spoke of his disappointment "given the amount of time and effort that I, and others, have put into planning the safety procedures for the return of children to the school".
The staff did not break any government restrictions but "failed to appreciate the bigger picture" of the spread of the virus, he said.
"I know each will be genuinely regretting the decision they took to attend what last year would have been an enjoyable event, but in the current situation was an ill-advised action to take, given their responsibilities to the children of the school and to their colleagues."
Mr Aspin apologised to parents for the "error of judgement".