A father attacked by a group of thugs while celebrating his birthday requires a jaw reconstruction to talk and eat again.

Billy Hales was transferred to Wellington Hospital after being brutally beaten when he was dragged from a car and hit over the head with a wooden plank on a Palmerston North street shortly before 3am on Sunday.

The father-of-two was knocked unconscious and had a seizure while lying on the road. He suffered a broken jaw, brain swelling, internal bleeding and extensive bruising.

His attackers were not charged by police.

READ MORE: Car used as weapon during late-night Palmerston North brawl

In the hours leading to the attack, Hales had celebrated his 27th birthday at an inner-city bar with a small group of friends and family.

They were waiting for a sober driver near the intersection of Broadway Ave and Princess St when they saw a Pacific Island man hit a woman.

Sasha Potaka, one of Hales' friends, said a woman in their group shouted at the man to stop. But he instead turned his attention on them.

SASHA POTAKA/SUPPLIED The car has several dents and a broken side mirror.

Hales intervened when the man leaped at his friend. The two had a small scuffle, but the quarrel got out of hand when the man returned minutes later with about 10 others.

"It was like a whole rugby team running towards us," Potaka said.

As they got into their car, the pack of men pounced on the roof and windscreen.

Hales' door was ripped free and he was dragged from the vehicle. The men hit and kicked him, and used the wooden plank as a weapon.

"They were vicious. It was awful. They saw Billy and went straight for him. I've never seen anything like it in my life," Potaka said.

"I was terrified. I thought someone was going to die."

SASHA POTAKA Potaka's right eye was bruised after a police officer punched him in the aftermath of a group assault.

Police officers arrived a short while later, but the attackers fled on foot and only two were arrested. They were released with pre-charge warnings.

Meanwhile, Potaka and her friends supported Hales' head as he lay on the ground.

Potaka's husband, Jamie, ran up to an officer to ask for help. But he was punched in the face and put in handcuffs. Several members of his group were pepper sprayed.

He was then attacked by a police dog on a leash. Extensive bruising and bite marks cover his torso and upper thigh.

"[The handler] allowed it to bite him, pulled it off and then let it bite him again. It was absolutely disgusting," Potaka said.

Jamie was arrested and charged with fighting in a public place. He appeared in the Palmerston North District Court on Thursday.

SASHA POTAKA Potaka suffered bite marks and bruising to his legs and torso after an attack by a police dog.

Despite a large gathering of onlookers, Potaka said police failed to take statements from witnesses or others in their group.

Her brother, Kane Ross, was late to the scene. He was walking down Broadway Ave when he saw the dog attack.

"I was oblivious that it was actually my family," he said.

Confused, he ran over to ask police what had happened. He was arrested and later released at 6am with a warning.

He then went to Palmerston North Hospital to visit Hales before he was transferred.

"His face was munted. He was bleeding from the ear. The fact that none of the [gang of attackers] were arrested astounds me," he said.

Police are making inquiries.