At least 21 schools around Auckland have been closed after receiving “concerning emails” on Friday morning.

This comes a day after 15 threatening emails were sent to schools and hospitals.

Police have also confirmed Nelson District Court had received a threatening email.

The emails were the same as those received on Thursday, says a police spokesperson.

“As noted yesterday, police are confident that the emails being received are from the same source, and we do not believe there is any actual threat to the organisations receiving the emails.”

Police also confirm Nelson District Court has received a threatening email.

Schools closed/delaying opening this morning:

• Ōrewa College – In an alert on their website, Auckland’s Ōrewa College said due to health and safety, the school was to be closed immediately.

• Ōrewa Primary School – Ōrewa Primary School has also been instructed by police to close for the day.

• Stella Maris Catholic Primary School – Stella Maris Catholic Primary School, also in Auckland, confirmed to parents it had received a threat and will be closed on Friday. "While it is considered a low level threat, we are erring on the side of caution".

• Murrays Bay Intermediate School – Murrays Bay intermediate sent an email to parents, stating they had received a threat, and to not send kids to school until the school said it was safe to do so.

• Silverdale School

• Waitoki School – Waitoki School in Kaukapakapa, to the north of Auckland city, informed parents it had received a bomb threat. The school was closed but would reopen from 9am.

  "The police have advised us that the school has been thoroughly searched and there is no threat."

  The school will begin lessons at 9.30am and parents are asked not to drop off their children until 9am.

• Mairangi Bay School – Mairangi Bay School also received a threatening email and is closed. “We have procedures in place and the safety of staff and students is our priority” a notice on the school website read.

• Oteha Valley School

• Browns Bay School – An alert on the schools website states the school is closed due to a bomb threat.

• Stanmore Bay School

• Whangaparāoa Primary School – A Facebook post by Principal Kevin Cronan seen by Stuff states that the school had recieved a threat, and asked parents and caregivers to keep children at home.

• Dairy Flat Primary School – An email sent to parents stated the school had recieved a threatening email, and asked not to send students to school.

• Murrays Bay Primary School

• Long Bay College

• Gulf Harbour School

• Snells Beach School

• Helensville School

• Riverhead School

• Matakana School

• Glamorgan School

• Matua Ngaru School

A Mairangi Bay School parent says they received a notification that school will be closed for the day due to a bomb threat.

The parent says the school's closure means he has to explain what a bomb threat was to his nine-year-old daughter, and that the threat is likely a hoax.

"I don't want her to be anxious. In my head, I know there's no threat, there's no issue. I understand everyone has to take it seriously but it's frustrating that someone can do this by just flicking off an email."

He's glad his 16-year-old son has finished his NCEA exams. "I can imagine the disruption to all these kids who are sitting an exam this morning".

"Our kids seem to always be the ones paying the price for these things.”

The parent, a stay-at-home dad, says he might take his daughter to the cinema since school is closed.

NZQA deputy chief executive assessment Jann Marshall says the safety of students and staff is a top priority, but that each school has its own processes for handling a security lockdown, and these applied during the exam period.

"Students who are unable to sit an exam, or whose performance is impaired because of a security incident, can apply for a derived grade, or their school may apply for derived grades at scale to apply."

Other local schools were able to support some St Kentigern College students to sit afternoon exams yesterday (NCEA Level 1 Dance and NCEA Level 2 Earth & Space Science), and these students would be awarded the better of the grade they received through the exam and the derived grade.

On Thursday, threats were sent to 15 institutions, including schools and hospitals around the country.

Police say they are confident that the emails all came from the same source, but are still working to identify the origin.

“We do not believe there is any actual threat to those that received the email.”

Police say they are taking the matter seriously and that they appreciate it had been a nerve-wracking day.

“Staff are working with those impacted and each organisation may respond differently according to their individual circumstances and the information available to them.

”Inquiries into the matter remain ongoing and the complex task of identifying the origin of the email is underway.”

In a statement emailed to parents, St Kentigern College in Pakuranga college confirmed it had received a bomb threat.

The school was evacuated and closed for the rest of the day.

-Karanama Ruru and Caroline Williams/Stuff.