A 30-year-old man is in custody as police investigate a double homicide in the South Auckland suburb of Wattle Downs.

Officers were called to a property on Thursday where a woman and a man were found dead.

Detective Inspector Tofilau Faamanuia Va'aelua, of Counties Manukau CIB, said police are working to determine if the 30-year-old was involved.

"Police will provide further updates as they are available."

A neighbour said he saw a car "bolting up the street" before hearing gunshots.

Robbie was outside having a cigarette when the incident unfolded.

"We hear a car come bolting up the street and he stopped in front of that house there. He slammed on the breaks, got out ran up the drive and all we hear after that is 'pop, pop, pop, pop'."

Robbie said he then heard the car driving away and then the sound of a woman screaming.

On Friday morning, two officers with rifles were outside the cordoned-off home.

Police forensic and crime scene officers were also seen putting on shoe covers and entering the home just before 6.30am.

Emergency services responded to reports of a woman unresponsive at a house in Gambare Place about 1.45pm on Thursday.

The woman was pronounced dead at the scene and, during a search of the property, police found a man who was also deceased.

Va'aelua said the offender or offenders fled the scene prior to officers arriving.

Dianna Kereopa-Turner has lived in the street her whole life and told RNZ on Thursday she had just returned home when "havoc started going on" outside.

"We thought it was our nail gun for our sleepout that we're building going off ... and then it was quite loud.

"But no, it was shooting. All we heard was gun. Then my sister came out of her room and said 'somebody out there's shooting', so we gathered in whoever was loose around the house and stayed inside."

The victims had only just moved in to the street, she said.

"It's sad to know that whatever trouble was following them, obviously followed them right to the doorstep, and unfortunately it happened on this street where there's a lot of kids and a lot of elderly people."

Many residents were unable to return to their homes in Gambare Place and adjoining Volante Avenue due to cordons on Thursday.

Another Gambare Place resident, Bobbie, said she had been at the doctors and tried to return home about 2.45pm.

"The street was already closed off, so I thought, 'oh better shoot over to the school and pick up my niece', got over there and it was locked down as well."

Bobbie said they were allowed to go home just after 5pm.

She said, once home, she talked with neighbours and some were quite shocked.

While the cordon was in place, police were seen working behind a white tarpaulin on Volante Ave. Police later confirmed staff had moved the victims to a safe location, away from the scene, to render first aid, while other staff continued working to clear the scene and make it safe.

Va'aelua said the incident appeared to be isolated, but police were not able to "rule anything out", and were now determining the exact circumstances of the incident.

"This is an awful set of events and no doubt unsettling for everyone involved and the wider community."

Anyone with information on the incident that could help police with inquiries could contact 105.