The mother shot dead in Greymouth yesterday has been named by police, who have also released details of the armed man they allege is on the loose.

The female victim is yet to be formally identified but police say they believe her to be 43-year-old Hayley Williams of Greymouth.

It's understood that Williams was a mother-of-three.

Amanda Williams, a friend of Hayley Williams, described her as a "very kind and compassionate lady".

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"No way did she ever deserve that," she wrote on Facebook.

"I'm broken ... gutted... sick to my stomach."

Neighbours reported hearing one gunshot after the incident at a house on Marsden Rd, south of the Sinnott Rd intersection about 4pm yesterday.

The gunman is said to have fled the scene.

Now, police want to urgently speak with George Sean Warren, a 45-year-old described as Maori, of medium to solid build, 177cm tall, with short or shaved hair.

"Warren may be armed and should not be approached. Any sightings should be reported to 111 immediately," said Inspector Mel Aitken, Area Commander West Coast.

Earlier today police said they had found the vehicle the alleged shooter is believed to have used when leaving the Greymouth property where the shooting took place.

"We have also located an associate of the alleged offender, and he is helping us with our inquiries," Aitken said.

Aitken urged the public not to approach anyone seen acting suspiciously in the area and asked them to ring 111 immediately.

"If you have information which may help police locate the alleged offender, please contact your nearest police station."

Aitken said police believe the woman and the shooter were known to each other, but it was yet to be confirmed.

"Police are doing everything we can to support the family during this difficult time," she said.

An armed cordon remained at the house overnight. A scene examination is expected to take some days.

Police will give a press conference at 4pm.