Superintendent Chris Scahill has said police are investigating the source of the phone messages sent to six schools around the country that threatened bombings on February 24, 2015.

More than 30 schools have received a string of bomb threats in the past two days, police say.

Twenty-seven Northland, Auckland and Waikato schools were the latest to be targeted on Thursday.

These followed six bomb threats on Wednesday elsewhere around the country.

Initial indications are that the threats may have originated from overseas, police say.

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Police on Thursday said they were responding to threats "of a concerning nature" at "a number of schools" in Auckland, Northland, Rotorua and Waikato.

MATTHEW CATTIN/FAIRFAX NZ Students at Silverdale School on Auckland's North Shore were evacuated onto the netball courts following a bomb threat.

Kerikeri High School and Kaitaia Intermediate School in Northland; Glendowie School, Glen Eden Intermediate School, Orewa North Primary School, Silverdale School and Kingsway School in Auckland; Berkley Normal School in Hamilton; and Western Heights High School in Rotorua all received threats.

Several of the schools were evacuated, with parents notified of the incidents.

"We should make it clear that while such calls may display a New Zealand number, they can still be originating from overseas," police said in a statement on Thursday afternoon.

MATTHEW CATTIN/FAIRFAX NZ Police were called to Silverdale School after the bomb threat was received.

"As we stated [on Wednesday], similar incidents have occurred overseas in United States, and more recently Australia.

"Until police can rule out any actual threat, we must take all these calls seriously and respond accordingly. The safety of students, teachers and schools are our priority.

"We understand the fear and concern that this will cause, however we reiterate that so far we have not established any actual threat to any school."

TRACY HARDY/SUNLIVE Police have responded to hoax bomb threats to at least nine schools during the past two days.

Police said they attended all schools involved, and were working with school management teams on the appropriate response.

AUCKLAND SCHOOLS FACE THREAT

Glendowie School board of trustees chairwoman Dawn Garbett said the Auckland primary school received a threatening call about midday and evacuated all students immediately.

SUNLIVE Police officers guarded Brookfield Primary School following a hoax bomb threat on Wednesday.

Police had been called and the children would remain outside for an extended lunch break and sports on the field while they waited for their parents to collect them.

Garbett said it was likely Glendowie was just one in a string of randomly chosen schools to be hit with the hoax but they weren't taking any chances with student safety.

Glen Eden Intermediate School also received a hoax bomb threat on Thursday. Principal Maree Stavert notified parents and caregivers of the threat via email.

"Just before 12pm today the school office received a pre-recorded automated bomb threat similar to what has been received recently in other schools both in NZ and globally," the email said.

Police were called, the school was evacuated, and students and staff were able to return to school grounds shortly after 1pm.

A string of schools on Auckland's North Shore have also been targeted.

Orewa North Primary School, Silverdale School and Kingsway School in Orewa are lock down over bomb threats.

Silverdale School emailed parents shortly before 3pm. Students were evacuated onto the netball courts and parents were asked not to come to the school until further notice.

Police were in attendance following the threat and a police helicopter was seen circling the school.

One parent picking up her children said she had received no explanation as to why the schools were locked down. She said she was extremely concerned when she heard and it had been very traumatic.

Police escorted students off the grounds at Silverdale School and KingsWay Primary School to waiting parents and buses.

Pupils were excited to see armed police, the police Eagle helicopter and police vehicles with flashing lights.

"It was awesome. I saw a policeman carrying an assault rifle, with flashing lights and a red dot scope," one pupil said.

Shortly before 4pm Rodney police area commander Inspector Mark Fergus said all schools in the area had been released.

"We are confident the threat is over. We will be releasing more information later," Fergus said.

NORTHLAND SCHOOLS THREATENED

Deputy principal at Kerikeri High School, Daniel Wise, said a call came through shortly before midday, when a robot-like voice threatened the school.

Students and staff were evacuated to the field outside the school and emergency services were alerted, Wise said.

It took police and fire crews about 30 minutes to give the 1550 students and staff the all clear.

Parents were notified and teachers clearly explained to students what had happened.

"Obviously it's really concerning, especially that they seem to be targeting schools," Wise said.

Kaitaia Intermediate School principal Sue Arrell said the automated call came into the front office about 11.30am.

Luckily, staff were aware of the string of hoax calls and were able to take a "measured approach", Arrell said.

The school called police and security staff, who checked the school grounds and gave the all clear about 12.30pm.

Students were not evacuated but the school ran an emergency evacuation drill after police had left and Arrell explained what had happened.

"I think it's dreadful. It's people just trying to scare people," she said, adding that students and staff now felt safe, happy and not threatened.

WAIKATO SCHOOLS EVACUATED

Schools in Hamilton, Rotorua and Morrinsville also faced threats on Thursday morning.

David St School in Morrinsville sent a letter home with children confirming the school had been the target of a threat in the form of an automated phone message originating from France.

The school was temporarily evacuated and the school was told by police that "the risk to students and staff was zero".

Berkley Normal School in Hillcrest in Hamilton and Western Heights High School in Rotorua were also evacuated.

In an email to parents, Berkley principal Nathan Leith said the school received a hoax bomb threat "similar in type to hoax bomb threats being received by other schools around the country".

A Rotorua police senior sergeant said police responded to the hoax call at Western Heights High.



"They've been all over the North Island," he said. "You have to treat these things seriously."

NELSON ALSO AFFECTED

Victory School in Nelson also received a threat about 1.30pm but the school wasn't evacuated.

Tasman police district communications manager Barbara Dunn said the school activated their emergency plan and no threat was found.

Victory School principal Helen Taylor-Young declined to comment.

LINKED TO EARLIER THREATS?

Thursday's calls may be linked to similar events from Wednesday, which saw calls made to six schools around the country, police said.

Logan Park High School in Dunedin, Wellington High School in Wellington, Tamatea High School in Napier, Burnside High School in Christchurch, Central Normal School in Palmerston North, and Brookfield School in Tauranga all received threats about 12.30pm on Wednesday.

Police said they were aware of very similar incidents of so-called "robo-hoaxes" occurring overseas in countries such as Australia and the United States.

Superintendent Chris Scahill said that in most cases, schools overseas had received coordinated calls with an automated, recorded message making a threat, often in a robot-like voice.

The Ministry of Education said on Wednesday that parents could be assured of their children's safety.

Deputy secretary of sector enablement and support Katrina Casey said the ministry contacted affected schools and offered support.

"We'd like to assure parents that they can continue to feel confident in sending their children to school, and that schools have the processes and systems in place to manage any threat to student safety."