Police allege the three victims were kicked, punched, stomped and hit with weapons.
They suffered moderate injuries, including a broken finger, lacerations and abrasions. One was also knocked unconscious for a significant time.
Hunter on Monday said police were still seeking footage of the incident and believe people recorded the incident on their cellphones.
An online portal has also been set up for people to upload photos or videos directly to the investigation team.
“If you have video, or photos, please go to leopold.nc3.govt.nz/,” he said.
Alternatively, anyone with information to assist police can contact their 105 phone service and quote the file number 240803/0149.
Information can also be provided anonymously through Crime Stoppers on 0800-555-111.