A South Auckland School acted within minutes of finding out one of its pupils was positive for Covid-19, the principal says.
The child attended Chapel Downs Primary School from 8.30am to 9am on Monday morning before being collected by their family.
The positive test result came back later the same day.
Auckland Regional Public Health Service (ARPHS) said Chapel Downs School families were alerted as soon as it was confirmed that the pupil attended the school on Monday morning.
The school has now been shut down for deep cleaning and anyone who was present at the school on Monday morning is being advised to stay away from people outside their bubble until they are tested and receive a negative result.
A "very small" number had been determined to be close contacts but no number was specified by ARPHS.
The child and their family are now in isolation, with health authorities monitoring.
A pop-up testing centre set up at the school this morning has been swamped with parents and children coming for a test.
But parents are angry that despite the pupil testing positive on Monday afternoon, they were not notified until Wednesday.
- If you have symptoms of the coronavirus, call the NZ Covid-19 Healthline on 0800 358 5453 (+64 9 358 5453 for international SIMs) or call your GP - don't show up at a medical centre
Ramona Ah Fook, a pregnant mother of two children at the school, told RNZ that morning period is busy and kids from all classes would be near each other.
Ah Fook was furious it took two days to find out about the positive case.
"They have absolutely no right to keep our kids, or to allow our kids, to go to a place where they know Covid existed for two whole days. And now they've decided to close down the school for a thorough clean."
School principal Vaughan van Rensburg told Morning Report he could not go into details why the child arrived at school on Monday morning and was then picked up half an hour later by their family.
He first learned of the child's positive test at 2pm on Wednesday from ARPHS and was liaising with them to find out the exact circumstances.
"I can just confirm to our community and reassure them as soon as we received the information we moved extremely quickly within minutes to let them know the exact situation."
A grandparent who is taking her two grandchildren for a test has told RNZ the school is not to be blamed amid accusations that it didn't act fast enough.
"I'm sure the school has tried to do the best they can as soon as they got the information. I don't blame the school at all - you shouldn't blame anyone. It's not our fault the virus is here so you've just got to get on with it."
The school has had a thorough clean which will be completed by this afternoon and van Rensburg hopes it will reopen on Monday morning.
Read more about the Covid-19 coronavirus: