Police are reviewing all assaults on women in the Auckland area to see any of them are the work of a vicious serial attacker targeting women out exercising in the East Coast Bays area and west of the city.

So far, four are believed to be linked: three on or near the Murrays Bay walking track, and a fourth at a park in Massey.

In the attacks, a man has grabbed women from behind and pushed them to the ground - knocking them senseless and causing serious injuries, including a broken collar bone, broken nose, dislocated shoulder and concussion.

Police have increased patrols in the area and are warning if people see anything suspicious call 111.

"They are frenzied in the force used and just in the speed of the attacks," Detective Senior Sergeant Callum McNeill told Checkpoint.

"On each occasion a male has approached each of the women who have been by themselves, they have been alone, he's gone up behind them with some speed, he's picked them up, knocking them or driving them into the ground and then unleashed punches to them, leaving them in a pool of blood before running off," Detective McNeill said.

"It's happened all very quickly."

The attacker has said nothing to the victims, he said.

"We're keeping an open mind as to [whether the attacks were sexually motivated] but in particular around East Coast Bays, the tracks weren't very large so there was nowhere to potentially take the females," Detective McNeill said.

But he said there has not been anything sexually-motivated that police have found in the attacks.

The series of attacks has happened over about four weeks. The first two on a walkway in the Murrays Bay area.

One of the woman was jumped while jogging at 7:45am on October 10, the other at 10.45am on October 24. The third attack was close by, between Browns Bay and Beachwood Roads, on November 8 at 4:40pm.

A woman just minutes behind the jogger found her roadside.

"She was in agony, she was on the berm, she was half-sitting, and she was just holding on to her shoulder. She had a sore ankle she said, and I could see she had bleeding from her knees and elbows, and she was just in excruciating pain," the woman, who wants to remain unnamed, told Checkpoint.

"She had come up the stairs from Browns Bay, and just as normal, had her headphones on. She saw a guy go past her down the steps, she just kept on going and suddenly she got hit from behind, and as she fell down he just pummeled her, he laid into her with his fists. I just couldn't believe it.

"In broad daylight, she had been hit by a stranger, for no reason, absolutely no reason."

Investigators now believe an assault on a woman in Moire park in west Auckland's Massey on October 26 may also be his work.

"Exactly the same [modus operandi] – the offender has run up behind her, grabbed her, driven her into the ground and then punched her around the head several times before running off," Detective McNeill said.

Police are trying to figure out the link between the areas and times, he said.

"It may be because he lives in one area and commutes to the other area for work."

Police describe the man they're looking for as olive-skinned, aged mid-20s to mid-30s, around 180cm, chubby, and possibly with his hair in a 'man bun'.

"It's concerning that we've had four attacks. We haven't had anything since November 8 but I'm concerned, they're serious attacks, they're appalling, unprovoked, attacks on unsuspecting women minding their own business," Detective McNeill said.

"As part of our wider investigation we're looking at all assaults on women in the Auckland area just to see if there are any links."

He said he cannot rule out the possibility there are potentially more attacks.

"We're not going to tell women what they can and can't do, we just want them to be alert, to be aware of their surroundings, have a look around and if they do see anything suspicious, then report it to the police."