Key Points:

A policewoman is in Middlemore Hospital with "horrific injuries" after being bashed up by a naked teen in Pakuranga yesterday.

Police received a call from a superette that had been hit twice in six minutes by the 16-year-old on a bike, armed with what is believed to have been a toy pistol.

They then received a tipoff about where he was. When the officer and a male colleague arrived at his house, the boy was in the shower. He fled wearing only a towel.

They chased him, splitting up as they ran.

When the policewoman tried to stop the teen, he whacked her many times in the face.

She suffered severe injuries, including to her eyes.

Police communications staff heard her screaming over the police radio for about two minutes as she was being pummelled.

Three people nearby also heard her. "She was yelling, 'Please don't hit me... please help'," one said.

"The guy was straddling her, just beating her face - left, right, left, right."

After yelling at the boy to stop, one of the three advanced on him. He fled.

Senior Sergeant Millie Whear said the officer was incredibly brave for holding on to the attacker while she was being hit.

Police dogs caught the boy, who was by then naked, in a property neighbouring a reserve at the end of Pandora Place.

The teenager is alleged to have earlier stolen from the dairy and then returned within six minutes to rob it. He also allegedly broke into a nearby home.

The owner of the Tiraumea Superette in Tiraumea Drive, Kamal Patel, said the boy arrived at 3.30pm and stole a bag of chips.

"We did not call the police as it has happened before," she said.

He returned six minutes later, riding a child's bike into the store with what is believed to have been a toy silver gun.

"He was very aggressive, swearing and out of it, banging his gun on the counter.

"He asked two customers for money and tried to steal cigarettes before leaving."

He did not manage to steal anything.

Mrs Patel was terrified because her two young children were in the store.

Minutes later, police changing shifts in Manukau heard that one of their own was in trouble. At least 10 officers sped to the scene.

Resident Helen Cohen, a registered nurse, saw the female officer emerge from the Pandora Place reserve covered in blood.

"She had severe swelling ... couldn't see out of her eyes and was unrecognisable.

"She was very distressed and just wanted to call her partner."

Senior Sergeant Whear said it was very likely the officer would need surgery.

She was very grateful for the public's help in stopping the attack. One of those who ended the bashing said the officer "would have been a lot worse off if the fight had lasted longer".

Ms Cohen said she was surprised by the injuries the attacker inflicted, considering he was "a skinny guy. He must have been an angry young man."