Kamo High School, in Whangārei, went into lockdown after a "message" was received by the school.

The school went into lockdown about 11am and police and emergency service personnel were stationed around the school.

Staff and students were kept in the school gym and were released at 11.37am.

The school told parents the lockdown was a precaution and would update them when it could.

"Your child(ren) are safe and all appropriate measure are in place. We will advise of any updates as they come to hand. Please stay away from the school."

The nature of the message the school received was not known.

However, police are investigating what they have now confirmed to have been a bomb threat at Te Puke High School this week. Armed police were called to the Tui St college on Monday morning after the principal said the school had received a malicious email. Te Puke Police officer in charge Sergeant Mark Holmes said inquiries were continuing.