Police are urging senior leaders in the King Cobra and Rebels gangs to hold peace talks and end the conflict before someone gets seriously injured or killed.

A turf war between the gangs has led to tit-for-tat violence where homes, cars and businesses have been targeted in drive-by shootings or firebombing with Molotov cocktails.

At least 12 attacks since the start of May have been confirmed as linked to the feud, say police, although the true figure may be higher as the criminal code of silence means no one from either side is talking.

Counties Manukau Detective Inspector Chris Barry says two squads of detectives are working full-time on the conflict, with numerous raids on the homes of patched members and associates of both gangs.

So far, Barry said one arrest has been made with a direct connection to the turf war.

A man appeared in the Manukau District Court last week charged with wilful damage to property with an explosive, in relation to the firebombing of a King Cobra's car in east Māngere on May 7 - the first known attack in the turf war.

He was also charged with possession of methamphetamine for supply and participating in an organised criminal group.

Although only one arrest has been made so far in direct connection to 12 attacks, Barry said a "large number" of gang members and associates from both sides had been arrested on drugs and firearms charges as a result of the police investigation.

Significant firepower had also been seized, including military-style semi-automatic rifles, although Barry said they had not been connected to any known shootings.

"We know that shotguns have been used, and rifles of various calibres," said Barry. "We're all aware that the gangs have access to a variety of unlawful firearms and that's something we are very keen to target them on."

Unlawful firearms were often kept at the properties of family and friends for safekeeping, said Barry, rather than at the homes of gang members, who knew they would be under scrutiny.

He encouraged anyone with information about the location of guns to come forward, even anonymously, and tell the police "before there is a tragedy".

Two King Cobras were treated for gunshot wounds in Middlemore Hospital on Tuesday. Despite neither man speaking with the police, Barry did not believe the shooting was part of the conflict with the Rebels.

"It's not always easy to establish [a connection]. Just because something happened at the address of the King Cobra member, we can't automatically say, 'Well, that was the Rebels'," said Barry.

"Personally, I don't think [the Tuesday shooting] fits within the conflict we are aware of."

Barry also urged senior leaders in the King Cobras and the Rebels to hold peace talks before the violence spirals out of control.

"Those conversations are happening. It's about getting the right people around the table who have the influence to put an end to the violence," said Barry.

"Members of these groups have friends and family in the community too, so hopefully they can influence them as well.

"This is about the safety of the community. There are so many good people, trying to do the best thing, and it's not easy out there at the moment. This is the last thing the community needs."

Barry said it was difficult to pinpoint the catalyst for the conflict, but the Herald understands tensions were inflamed by a social media post by a senior Rebel, which staked a claim to Māngere, a suburb the King Cobras consider to be their territory.

Around the same time, a King Cobra "patched over" - or switched allegiances - to the Rebels, which is a rare move considered highly insulting in the criminal underworld where loyalty is highly valued.

Founded in Ponsonby in the 1950s, the King Cobras is one of the oldest patched gangs in New Zealand.

The Rebels was the first Australian motorcycle gang to establish a presence in New Zealand, in late 2010, but in recent years has been bolstered by senior members deported from Australia.

It has been joined by other outlaw motorcycle gangs, such as the Comancheros and Mongols, and although these deportees comprise a relatively small proportion of the thousands of so-called "501s", nicknamed after the section of the immigration law used to remove them from Australia, dozens of them stamped their mark in New Zealand's criminal world.

Organised crime detectives believe the new gangs have a disproportionate influence because of their international connections, sophisticated counter-surveillance tactics and aggressive use of firearms.

New Zealand criminals have always carried firearms, but the arrival of the Australian groups has led to an escalation where rival groups are more likely to shoot at one another.

"We see that as a very undesirable shift in our criminal landscape," Police Commissioner Andrew Coster told the Herald in announcing Operation Tauwhiro in February to target firearms in the hands of criminals.

"While this is predominantly an issue between gangs and organised crime groups, people are dying and that's not okay. And, understandably, that causes fear in our communities. People should not have to live in an environment with this level of violence around them."

In the most high-profile clash this year, a member of the Head Hunters allegedly fired a pistol in the crowded lobby of the five-star Sofitel hotel on Auckland's waterfront. The Head Hunters, for so long the dominant gang in Auckland, were feuding with the Mongols at the time.

Although these crimes often go unreported unless the violence spills into the public, or the consequences are fatal, hospital data shows 350 people in Auckland have been treated for gunshot wounds in the past five years.

The proliferation in firearms also increases the risk for frontline police. Constable Matthew Hunt was fatally shot in West Auckland last year, the first police officer to be killed on duty for a decade. A Waikato colleague was also shot by gang members in another routine traffic stop.

The most recent attack, combined with police needing to confront other armed and dangerous individuals in Auckland and Hamilton, has reignited the debate on whether police should be routinely armed.

Police Association president Chris Cahill has called for more frontline police to carry firearms, and the return of the Armed Response Teams, although these moves have been ruled out by Police Minister Poto Williams.