Police have released sickening footage of a "violent and frenzied" unprovoked attack on Queen St, which left both victims unconscious.

CCTC footage of the attack, which occurred on Sunday, May 6, was previously described by police as "too graphic" to be shown to the public.

However it screened last night on Police 10/7 in a bid to find those responsible.

It shows the two victims at one stage lying unconscious on the central Auckland pavement while the group of eight men continue kicking them, even stomping on their heads.

Police 10/7 host Detective Sergeant Rob Lemoto said it was a "cowardly and ruthless ambush".

"The victims were both rendered unconscious, but this hasn't stopped their assailants.

"The fact the victims were lying on the ground still wasn't good enough. This group have come back for a second go."

In the early hours of Sunday, May 6, the two victims were walking towards the waterfront, when they passed a group of three males and two females, who were listening to loud music, Detective Constable Thomas Malcolm said.

The victims complimented the music, which led to a verbal altercation, but the victims were able to walk away.

Shortly after they were attacked by a group of up to eight men.

"It hasn't been a fight, it has been an assault," Malcolm said.

The first victim was kicked across his body, including in the face, and had his head stomped on. He became unconscious, but the attack continued.

His friend was also kicked in the face and head.

Members of the public managed to intervene and pull the attackers off the men, before they dispersed.

Malcolm had previously said footage of the assault, captured on CCTV, was too graphic for release.

"We know our community will be absolutely shocked by this crime - two innocent members of our community simply having a night out when they were attacked," he said shortly after the attack.

"Given the random nature of this attack we believe this could have happened to anyone so it is important we identify these offenders and hold them to account as soon as possible."

Police had tracked a group containing some of the men directly involved in the assault starting outside Danny Doolans on the waterfront about an hour earlier,

They then travelled along Quay St to a walkway on Customs St leading to Queen St, and continued towards Wellesley St.

Three men were "especially violent" in the attack.

One was wearing a yellow hoodie with a black vest over top, and camouflage shorts.

Another was wearing a black cap, and a grey baseball top.

The third was wearing a tan shirt, with white T-shirt beneath and dark pants.

"Someone watching this will recognise these people and should give us a call, so we can prevent these people from doing this to anyone else, ever again," Malcolm said.

The victims were incredibly fortunate to have survived the assault.

"I have worked on cases with less violence, that have had much more tragic outcomes.

Both victims had made a good recovery, he said.

"But it could easily have been worse."

One was left in a critical condition after the attack.

Malcolm previously thanked members of the community who stepped in to help the victims.

"They put themselves in danger to prevent any further injury to these men and we commend their actions."

A witness at the time described thinking one of the victims was dead when he arrived at the scene.

"We thought something was going on so we ran down to have a look and there were two dudes on the floor getting booted in the head," Dennis Leau said.

"There was blood everywhere and they were booting them in the head, face and everything," he said.

"At first when I looked down I thought, 'oh shit, this fella looks like he is dead', but they were still booting him. I thought, 'that is enough, man'.

"He didn't move or do anything, even when they were kicking him in the face he made no noises or anything.

"Their faces were really swollen and mashed up and one of them was bleeding out of their ear. It was ugly.

"I was just thinking of the safety of those two guys."

Leau and a friend attempted to stop the fight.

"There was just us two against a whole group of people, but they looked like little boys.

"We were throwing them all off as some were kicking and some were standing over the top and throwing punches."

Malcolm can be contacted on 09 213 8683 - or witnesses can contact Crimestoppers anonymously on 0800 555 111.