Two pupils and one staff member from Selwyn Primary School are in isolation awaiting the results of testing for coronavirus.
The news was broken to the school community through a physical letter, on the school's Facebook page and on the school app.
The results of the tests were not expected until the weekend.
Principal Peter Barker said school would resume as normal and follow instruction from the Ministry of Health.
No other staff or students have been asked to self-isolate - "there's no need," Barker said.
The statement to the school community stated while there was no compulsion from the ministry to advise the school, the decided it was best to do so.
The protocols from the ministry for those who have been in contact with someone being tested for Covid-19 was there is no need to self-isolate as a matter of course.
"As with any school in New Zealand, if any of our students or staff test positive for Covid-19, the Ministry of Health steps in and advises the school around the process," the statement read.
The school will open tomorrow as normal and be closed for a teacher-only day on Friday.
The cleaning company the school contracted was following the hygiene procedures needed given the crisis, he said.
Hand sanitiser was available in all classes and toilets and there were also paper towels to dry hands with.
Parents had commented on the post online expressing gratitude for informing them, some saying they would not send their children to school.
Despite no advise from the Ministry of Health to shut the school, Barker said he "completely understands" if parents did not want their child to go to school.
"We're in pandemic status ... one of the reason that we communicated with our whanau in the way that we did was to keep them in the loop so they can make the decision on what they think is in the best interest of the students.
"I totally understand if our whanau err on the side of caution."
Barker said clear and constant communication with the school whanau about the facts of the unfolding matter was crucial and would be maintained.
He said keeping families informed was key in reducing panic.
Information on the results of the test would be released proactively to the school community through a social media post and the school app.