St Kentigern College in Auckland was deserted after threatening emails were received. Photo: RNZ / Felix Walton
Police said they do not believe that threatening emails received by several organisations today were a sign of any actual danger, and are working to identify the source.
In a statement, police said they were confident emails received by a number of organisations were from the same source, and Cybercrime Unit staff were working to identify their origin.
"We would like to reassure the affected organisations that police are taking this matter seriously and we appreciate today has been nerve-wracking," police said.
"We do not believe there is any actual threat to those that received the email, and we thank those affected for working alongside police. Enquiries into the matter remain ongoing and the complex task of identifying the origin of the email is underway."
RNZ understands police attended Auckland City Hospital, Wellington Regional Hospital and Bowen Hospital in the capital, and Burwood Hospital in Christchurch.
Bowen Hospital said police did a thorough sweep of the site before confirming it was safe.
The Ministry of Education was aware of one school, St Kentigern College in Auckland, that received the threatening email.
The college was evacuated. Some students were sitting NCEA exams at the time.
Paul Spain of Gorilla Technology said it would be "hard to know" where the emails came from or the senders' motivations.
"There's that small chance that somebody's trying to disrupt an exam, but this seems like too big a thing for an individual to do for something like that," he told Checkpoint.
"It is hard to find motivations other than maybe somebody that is just testing out and seeing whether they can have an impact with an anonymous email."
Spain said it was "very, very easy" to hide one's identity behind an anonymous email.
"[It] is something that can be done virtually at the drop of a hat if someone wishes to do so."
Without knowing the content of the emails, it was difficult to work out what the sender wanted, he said.
Paul Spain. Photo: © Jason Hosking
"I would say in many ways it's similar to the bomb sort of scares that have been around for decades, where somebody picks up a phone handset in a phone booth or something and calls in a threat and disappears before anybody can find them. It maybe falls into that sort of category.
"But if it has been done in a manner that is not able to be tracked by the police Cybercrime Unit, then of course, we're all largely left in the dark as to what the motivation is for it and who's done it.
"But there is always the potential that the Cybercrime Unit managed to track them back and that they haven't fully covered their tracks."