Officers were expected to remain visible in the city as the group moved on toward Ōpōtiki.
Police said a 30-year-old man was arrested after police responded to a report of suspicious behaviour on Aquarius Drive.
He was charged with possession of methamphetamine, possession of utensils for drug use, unlawful possession of a firearm and possession of an offensive weapon, and is due to reappear in the Rotorua District Court at the end of the month.
In a separate incident in the evening, police spotted a vehicle in the Western Heights area that had been reported stolen the previous day.
When signalled to stop, the driver allegedly fled, prompting police to pursue.
The vehicle was spiked and brought to a stop at Harrold Cres, where two youths were arrested.
Police also arrested three people on outstanding warrants, and another for breaching court-imposed conditions.
One person had their vehicle impounded and was summoned to court for driving while disqualified.
Inspector Tristan Murray said the presence of officers monitoring the gang gathering did not mean other offending would go unnoticed.
Police urged anyone witnessing illegal behaviour to call 111 immediately. Non-urgent reports could be made through 105, either online or by phone, or anonymously through Crime Stoppers on 0800 555 111.