Bayfield High School is in lockdown after receiving a threatening email on Tuesday morning.

Armed police were at the site and accompanying students from the school, which has closed for the day.

A police spokesperson said they were alerted at 8.17am.

"Police are making enquiries into a threatening email sent to Bayfield High School this morning," the spokesperson said.

"Police are working to establish the origin of the correspondence. Cordons are in place and a visible police presence will be in the area while enquiries are ongoing."

A message on the school's website said it had closed the school and any students not already at school should stay home.

"School is in lockdown effective immediately. As a precaution we are going to close the school for the day," the message said.

Acting principal Mike Beagley later said a "managed evacuation" had been carried out.

"Our thanks to all parents and caregivers for their support and help in making this run smoothly.

"At this stage our intention is to have school as normal tomorrow,but this is subject to an all clear from the police which we hope to receive later today."

Staff and students were asked to "remain off-site" until further notice.

Police said they were working with the Ministry of Education, and would remain at the school "while enquiries are ongoing".

Main image (RNZ/Tess Brunton): Police turn cars away from Bayfield High School, which was in lockdown on Tuesday.