Police warned a Paraparaumu family not to hold a teenage birthday party when they realised it had gone viral on Facebook, but the family went ahead anyway.
The party descended into a mass brawl and, when police arrived, revellers challenged them with a haka.
A bottle was thrown at an officer, a flick-knife was found on a partygoer, and three people were arrested.
Caleb Phillips-Millan invited 30 people to his 16th birthday party at his home in Wairere Grove on Saturday night, but up to 100 turned up after word was put out on Facebook and through texting by some of his friends.
Senior Sergeant Alasdair Macmillan said police advised Caleb's mother, Karen Millan, last week not to go ahead with the party, or change the venue, but she insisted everything was under control.
Police were called to the house shortly before midnight and were confronted by about 30 partygoers, aged between 14 and 20, fighting on the street.
"An unidentified person threw a bottle, narrowly missing a police officer, but hitting a patrol vehicle, causing minor damage," Mr Macmillan said.
Two 18-year-old youths were arrested for disorderly behaviour, and a 19-year-old found with a flick-knife was charged with possession of an offensive weapon, as well as disorderly behaviour.
Ms Millan, who has six children, has vowed never to hold a teenage party again. She praised the police response after the party "went crazy", blaming some of those who had also been at a riotous party in July for 18-year-old twins Rhythm and Heaven-Leigh Hartman.
About 200 partygoers, from as far away as Porirua and Otaki, turned up to that party after it was advertised on Facebook.
Mr Macmillan said one of the twins was at Saturday's party.
Ms Millan said police were terrific.
"It was good police were there so it did not get out of control like the riot. It was the same kids at the riot who came here. We expected the worst and planned for the worst."
She organised for some older people to act as bouncers, but said things got out of hand because of "just a few gatecrashers".
"Caleb knew a couple of the older guys, but they brought in heaps. As soon as the fighting started, all the good kids backed off, so the bouncers shoved the others to the gate and closed it."
Caleb said: "It was all right till an older group turned up and caused fights. Bouncers kicked them out on to the street and called the cops. That is what happens at parties, fights . . . police get called."
A neighbour, who did not want to be named, said a group of partygoers performed a haka to challenge police, and some hurled paintballs at her husband's car.
"I told them to leave our bloody car alone. Where do 16-year-olds get the alcohol and cigarettes from? They can't buy them.
"Where did the parents think their kids were? Young girls were talking about getting laid that night."
About 45 minutes later, police were called to a house in Tieko St, Otaihanga, after receiving reports of fighting. They found several drunken teenagers, some as young as 14, who were returned home to their parents.
About 10.15pm on Friday, police were called to a house in Clunie Ave, Raumati South, where a group of uninvited guests, aged between 16 and 20, turned up.
Advice for parents whose teenagers are going to a party:
Find out where and when it is taking place.
Get a phone number and make contact before the party.
Establish rules about drinking.
Drop off and pick up kids, arrange alternative transport, or provide taxi money.
Discuss peer pressure about "getting off your face".
Make sure children can ring you any time.
HOW TO AVERT A RAGE
Police advice for parents holding teenage parties:
Agree on guidelines together when planning the event.
Ensure written invitations are issued for organised parties, with a footnote saying the invitation is for that person only.
If alcohol is being made available, ensure it is not provided to minors.
Alcohol should be served by adults to ensure some control over how much is being consumed.
Ample food should be provided
Police should be advised a week before, supplying time, date, numbers expected and contact details of a responsible adult.
If unexpected people turn up, or there is any sign of trouble, contact police.
Some form of transport home should be arranged for partygoers.
If a large event is planned, security should be organised.
Realise that, once a party is put on Facebook, it is open to all and sundry.
- © Fairfax NZ News
Pals and playmates (pictures)
Reacting to a sudden cancellation
New Zealand's best deck built yesterday
Appreciating Tony Allen
The meaning of blogging