Within 30 minutes of the email going out on Saturday morning, Ellery said she knew about the leak.
"Of course, our first course of action was to work with SMS, our student management team to try to pull the email back ... it didn't work so since then we've just tried to mitigate the level of stress we're causing everybody and any potential risk," she said.
Following the leak, Ellery sent out an email addressing the error, calling it a "massive human error", and asking for parents to delete any information not pertaining to their child.
She said printing, forwarding or sharing any of the information would be illegal and in breach of the Privacy Act.
Ellery said the privacy commissioner had been notified of the incident and actions had been taken to restrict exposure of the information, with police also advised in case the safety of anyone in the document was compromised.
She wanted to assure parents over the coming week she will be working with the student management team to ensure the production of documents like the one in the leak will require a passcode in the future.
A member of the school's Board of Trustees, Kerralie Adam, said the focus of the school was to support the students and parents who had been impacted by the incident or the subsequent national media coverage.
"Obviously as a school, we deeply regret this incident as the school has always taken the privacy of its students seriously," Adam said.
As for the board, Adam said they were looking to conduct an urgent review of their student management system to find how the document was created and sent in error.
"If there are technical or procedural systems that need to be changed, we'll do so urgently to ensure this can't happen in the future," she said.
She said the review of the system was being undertaken as it should not have been so easy for it to create a document with such personal information.
"So we're looking at our student management system to try to understand how the incident was able to happen in the first place because that is of significant concern."
Mikaere said the school was taking the matter extremely seriously and the ministry was providing advice and guidance.
Ellery also asked any parents with concerns about the leak to email her directly at elleryk@wi.school.nz.