Police said yesterday attendance at the event could have been controlled better and it appeared too much alcohol was available to underaged teenagers.
In a written statement, parents' spokesman Barry Dryden said "outside parties" were to blame for problems outside the hall.
He did not respond in his statement to a query from the Otago Daily Times about the amount of alcohol available inside the hall.
Constables Martin Barham and Melanie Twyman were called to Hawea Flat about 9.30pm and shut down the private party after they arrived.
While they were inside the hall, the windscreen of their unattended patrol car was destroyed, apparently by thrown bottles.
Mr Dryden said only ticket-holders could get entry, parents attended and food and entertainment were supplied all night.
The event was discussed with Wanaka police with regard to control and police attendance, and a bus was organised to take people home, he said.
"Influence from outside parties caused the problem outside the hall but internally the party was great and being enjoyed by all attending . . .
"At 10.30, after discussions with police, it was deemed that the outside influence was causing too much trouble, apparently damaging a police car. It was decided to close down the party and transport party-goers home," Mr Dryden said.
A resident, who declined to be named, said there were more than 80 young people at the party and several verbally abused police.
He said the parents supervising the party could have exercised more control over the teenagers' behaviour, Senior Constable Ian Henderson said yesterday he went to help his colleagues after they reported their patrol car was damaged.
The party was over when he arrived.
He believed up to 120 people might have attended and said it was disappointing it had got out of control when parents had sought guidelines beforehand.
Snr Const Henderson said his colleagues were not threatened but some minor name-calling occurred.
The police wanted young people to enjoy their "milestone" birthdays but they also wanted to encourage parents take charge and not fear imposing their own rules about attendance and alcohol consumption at underage teenage parties.
Things parents could do included removing alcohol from guests at the door and serving it back to them, recording how much they had served each person, he said.
Invitations should provide clear entry requirements and those who left the venue should not be granted re-entry "so you can't go out and smoke weed or scull the rest of your six-pack".
The biggest problems came when uninvited guests congregated outside.
If that happened, police should be called, he said.
