A 37-year-old man faces murder charges after a woman's body was found with a gunshot wound.

A sawn-off shotgun and ammunition were allegedly found in the man's car when NSW Police took him into custody in the Hunter Valley region on Saturday night.

The arrest came after emergency services were called to a home in Kearsley on Friday night.

Officers found a 39-year-old woman dead at the residence.

Police on Saturday alerted the public that they wanted to speak with a man before they received a tip that he had been seen in Bellbird.

Hunter Valley Superintendent Steve Laksa said the death of the woman had involved a "traumatic incident".

"It was quite horrific for family members, all involved, and her three children," he told reporters on Saturday.

One of the children is understood to h

See Full Page