A drone almost took out the police's Eagle helicopter in the early hours of Tuesday morning.
Police say the Eagle helicopter pilot was flying over Spaghetti Junction when they had to take evasive action. The drone had come within 10m of the aircraft, which was more than 400m above the ground.
It's believed two other drones were nearby.
"The pilot and crew were shaken after evasive action was taken," police said in a statement.
The Eagle was grounded and operations suspended for the rest of the shift while an investigation took place.
"Our police helicopter is responsible for saving lives and keeping our community safe," said Insp Jim Wilson, acting district commander.
"The actions of these people in flying a drone dangerously close to the Eagle helicopter is totally irresponsible and police will investigate thoroughly."
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They will work with the Civil Aviation Authority to find out what went on.
"This could easily have ended in a tragedy and it is a worrying reminder of the dangers of flying drones near other aircraft."
Quiet night elsewhere
Otherwise police say it was a quiet New Year's Eve across the country, with no other "significant issues or incidents" reported to them.
Most of their work was dealing with minor disorder, liquor ban breaches and intoxication.
" Large crowds at Rhythm and Vines were generally well-behaved, with great cooperation between agencies and event organisers," police said in a statement.
A bad batch of counterfeit ecstasy was intercepted at the festival's gates, perhaps saving unlucky partygoers from having to make a trip to hospital.
No arrests were made at the popular event, but there were four arrests in Gisborne itself.
Police were happy with the crowds in Whangamata, with about 1000 revellers behaving well. Only a handful of arrests were made across the Coromandel Peninsula, and there were no issues in Waihi, Whitianga, Pauanui and Tairua.
Large crowds in Mt Maunganui didn't result in large problems, and celebrations in Nelson Bays were also held largely in "good spirits", despite 18 arrests for drunk and disorderly offending.
About 1500 people gathered in Hagley Park to see in the new year, with no arrests. Crowds in Akaroa, Hanmer Springs, Twizel and Timaru were also well-behaved.