Residents near the scene of a "disorder event" in Rotorua that left three people seriously injured have reported hearing screaming, revving, smashing bottles and calls for an ambulance.
One said he saw vehicles appearing to be used in attempts to hit people.
Rotorua police field crime manager Inspector Lindsay Pilbrow said police were called to Tania Cres, Western Heights, about 2.30am on Sunday.
Pilbrow said police found people injured, and damaged vehicles and fences. He said the offenders had fled in vehicles.
A Western Heights resident told the Rotorua Daily Post she heard the sounds of "a normal party" when she went to bed, but by the early morning, it had escalated.
The resident "woke around 2.20am-ish to the sound of chanting". She said she could hear a gang slogan being chanted.
"Then the women started screaming and bottles breaking. Cars started to rev and do burnouts."
Another resident said he saw an argument that devolved into what appeared to be three cars trying to run people over.
He said they were on the street and the footpath and seemed to him to be trying to hit people.
It was too dark for him to see if anyone was hit, he said.
He said the cars fled the scene when police sirens were heard.
Another resident reported hearing a group of people arguing, followed by a scream and a woman yelling that they needed an ambulance.
A resident who lives a block away reported being awoken by "a few loud bangs and then a woman screaming, men yelling, and cars being smashed up".
The Daily Post agreed not to name the residents.
In a statement on Monday morning, police appealed for information following the "disorder event".
Pilbrow said on arrival police established there were multiple areas where activity had taken place and a number of injured people who had been assaulted.
He said three people were transported to hospital with serious injuries suffered from the incident. One remained in hospital, the statement said.
"We want to reassure the public that we take this behaviour extremely seriously."
Witnesses or anyone with footage that may help police were asked to call 105 and quote file number: 220206/0704
The Daily Post has sought an update from police on the investigation.