Violent threats to schools treated seriously: Police Minister

Police would treat seriously the violent threats received by multiple schools and organisations across New Zealand, including RNZ, Police Minister Mark Mitchell says.

Schools have been evacuated and parents asked to collect their children after the anonymous threats were made on Tuesday morning.

Detective Inspector Glenn Baldwin said police were investigating the threats.

"Police are aware of a number of emailed threats to schools and other institutions across the country today," he said.

"At this stage, police perceive the threats to be low risk. The cybercrime team, supported by staff in other police districts, have initiated an investigation and are working to determine the source of the emails," Baldwin said.

Mitchell said police would be determining whether the threats were a hoax or someone wanting to disrupt schools, and he expected it would be treated seriously.

"I haven't seen them myself, but yes, I understand that police are looking into that ... I haven't seen any information on that myself, though," he said.

"There's people out there with way too much time on their hands that might turn their mind to putting some sort of hoax call in ... for whatever reason, and obviously it's disruptive, it is serious, and so you know the police will look into it and try and identify who's behind it."

There was a possibility the threats had come from overseas but he had seen no evidence of that, Mitchell said.

In a message posted on Whangaparāoa School's website, principal Kevin Cronin said it had received an anonymous bomb threat.

"Even though we doubt the validity of the threat, we feel our role is to make sure that our children and staff are safe," he said.

"The office is not manned. For this reason we ask you to come to the school field area and collect your child.

"You will need to touch base with your child's teacher and sign them out. If someone else is collecting your child, they will need to give the teacher their name."

Orewa College said it was in lockdown because of an "ongoing security incident".

"Please do not come to the school or phone the school as you will not be attended to," the school said.

"We are actively working with the NZ Police."

Christchurch Girls High School went into lockdown around 10am but has since confirmed "all students, staff and persons on-site are safely accounted for".

Acting principal Sonja Bailey said it was advised by the Ministry of Education after it received a "a threatening email".

"During this period the police were onsite and have assured us that we are safe to resume normal operations," she said.

The lockdown was lifted around 10.30am.

Several media organisations, including RNZ, received threats.

Earlier this year, an Invercargill teen was arrested for allegedly sending nationwide bomb threats to several organisations including schools and the Department of Corrections.

Ara Institute of Canterbury also received a bomb threat on Tuesday morning resulting in evacuations of its Christchurch and Timaru campuses.

Chief executive Darren Mitchell said Ara was working closely with police.

"We have evacuated all campuses and advised tenants and other campus users to go home as a precautionary measure," he said.

"We are not able to provide further details at this time as the police are leading the response. We will provide updates on our website and via official staff and student channels as confirmed information becomes available."