A vehicle stop by police has led to firearms being seized, vehicles impounded and charges laid against a patched King Cobra gang member as part of Operation Cobalt.

Operation Cobalt was set up in June across Auckland, with smaller teams around the country, to tackle the growing violence between gangs and intimidating behaviour in public.

The operation staff have being investigating a recent firearms incident and frontline officers from Counties Manukau located and stopped a vehicle of interest in Flat Bush last week.

"Police have conducted a search of the vehicle and located a revolver and ammunition inside. This has led Operation Cobalt staff to conduct a further search warrant at a nearby Flat Bush address," said Detective Inspector Aaron Proctor.

"A sawn-off shotgun and cartridges have since been recovered by Operation Cobalt staff following enquiries at this address."

Three "late model" European cars were also impounded.

The 36-year-old King Cobra member, who was a passenger in the vehicle, has been charged with two counts of unlawful possession of a firearm and has also been charged over unrelated driving offences.

The 27-year-old driver has also been charged in relation to unrelated offending.

"This is a great example of police staff working together to achieve the aims of Operation Cobalt in targeting unlawful activity," Proctor said.

"While there is a team of dedicated Operation Cobalt staff across the country, it also involves a whole of police approach to suppressing and disrupting this illegal activity."

Proctor said enquiries into the original firearms incident were ongoing - a firearm was reportedly presented from one of the impounded vehicles in the Ōtara area earlier this month.