The sword used was thought to be a ceremonial one, Detective Senior Sergeant Ross Patterson of the Hamilton CIB said. Police are seeking the public’s help in locating the alleged attacker.

A woman who was attacked with a ceremonial sword in her home has undergone surgery and is surrounded by family at Waikato Hospital.

The woman's nephew Brad Morgan said they were unsure of the outcome of the surgery at this time but his aunty had strong support from friends and whaanau in New Zealand and Australia.

"She would be very appreciative of all the heart warming comments and tautoko from everyone," he said.

SUPPLIED Manjit Singh was arrested by police after a woman was attacked with a sword.

Her alleged attacker was Pukekohe man Manjit Singh.

Police arrested a 47-year-old man in relation to the attack on Thursday night, in Favona, South Auckland.

"[We are] so glad he got caught and he can't hurt anyone else."

MARK TAYLOR FAIRFAX NZ Armed police guard the scene at a Sadler St house.

The 50-year-old Hamilton woman was taken to Waikato Hospital with severe injuries to her head and arms following the assault with thesword at her house in Fairview Downs.

"She will require significant treatment at the hospital," Detective Senior Sergeant Ross Patterson, of Hamilton CIB, said.

But the injuries would have been much worse if a family member didn't intervene, he said.

MARK TAYLOR FAIRFAX NZ Police have cordoned off the home where a woman was allegedly attacked with a sword.

The man believed responsible for the attack was also under mental health care and was believed to be armed with a handgun and considered dangerous.

He will face a number of charges including wounding with intent to cause grievous bodily harm and breaching a protection order in relation to the incident of the attack with the sword.

He will appear in the Hamilton District on Friday.

Detective Senior Sergeant Ross Patterson of the Hamilton CIB said it was believed the man responsible for the attack had been in the Counties Manukau area.

Police became aware of the man's whereabouts when he was identified by members of the public and was detained until police arrived.

The 47-year-old had also been a patient atMason Clinic, run by the Waitemata District Health Board.

"The Mason Clinic and the Ministry of Health have confirmed that the man sought by Hamilton police for an alleged serious assault on his partner was under the care of forensic mental health services," they confirmed in a statement this afternoon.

"A formal investigation into the incident will be announced."

Emergency services were called to the modest single level white brick home in a quiet residential street of Fairview Downs about 8pm on Wednesday.

"At this stage it appears Singh has gone to the property yesterday (Wednesday) and at about 8pm, emergency services were called following the attack.

"We believe the woman has been assaulted with a sword and as a result suffered serious injuries. She is currently stable in a ward in Waikato Hospital at this time."

Singh was thought to have been at the house for some time before the attack, Patterson said.

The sword used, which was understood to be ceremonial, had been in inside the house and not brought with him.

A neighbour, who did not wish to be named, said the woman appeared to be badly beaten when she was helped out of the house by two police officers last night.

"It's a bit scary. She looked pretty beat up, she was struggling to walk and couldn't see."

"I think it was a serious assault - her face as she was leaving was horrifying. From the light inside the ambulance, I am fairly sure she had injuries to her face."

The resident had just put her five-year-old son to bed when she saw the flashing lights outside the home.

"We had our dog inside and she got a bit growly. It would of been after 8pm and I didn't realise anything was happening until the cops got here."

She said the woman had lived at the home for a while with her two teenage children, understood to be girls. One of her daughters was hunched over and appeared upset as paramedics went to and from the ambulance.

"Both the girls were there, one looked quite upset. It looked like the other was organising things for her mum. As far as I could see it was just her injured, the other two both went in the ambulance with her."

"That poor woman, that is horrible, nobody deserves that kind of treatment."

Sadler St was typically a quiet place where most residents knew each other, she said, but the injured woman tended to keep to herself.

"When I woke up this morning there was a cop out there with a rifle, so I bundled my kid off to school.

"It was a shock. It is a quiet neighbourhood, you don't generally see armed police around as there is not a great need for it."