Loud booms erupted in Kaipara this week, as the Royal New Zealand Air Force dropped bombs during a training exercise.
The 14 bombs, weighing 500 pounds each, fell on the remote Kaipara Air Weapons Range from an Orion aircraft.
Air Force squadron leader Mark Chadwick said the exercise was to ensure personnel were up-to-date with their warfare training.
"It's for air and ground crews to gain currency and proficiency in preparing, loading and deploying the weapons from the aircraft."
Mr Chadwick said the bombs were designed to arm and detonate on impact with the ground, but a couple didn't this week.
"Every training, a small percentage of weapons don't explode.
"We've got contingency procedures for that, where we get personnel in there, find the weapon and dispose of it appropriately."
Mr Chadwick said the public was banned from the weapons range at all times.
"The explosions were quite significant."