About 20 police officers are investigating the death of a woman at her Upper Hutt flat early this morning.

Photo: RNZ

A homicide investigation has been launched into the death of 30-year-old woman.

She was assaulted with a weapon, but not a firearm, and was found deceased at her home on Ward Street in Upper Hutt just after midnight, police said.

A post mortem would be carried out tomorrow.

Police said earlier they had been looking for three men who were heard shouting shouting and seen running from the property this morning.

Detective Senior Sergeant Warwick McKee said about 20 investigators were working to find out what happened in the lead up to the women's death.

He said he believed it wasn't a random act, and the men were there for a reason, but it was still unclear what that was.

A resident from a neighbouring house, Pradeeb, said he had returned home from work about 2am to find ten police cars and armed police outside the flat.

He said he approached one of the officers.

Photo: RNZ / Emile Donovan

"I asked him what happened, you know there was a homicide and I was worried if there's anything to worry about with families here and they said 'No, there will be police here throughout the day so there's nothing to worry about'."

Two officers, one armed with a rifle, were still guarding the property opposite Wallaceville Business Park this morning.

Police said they did not think any firearms had been used.

Two more officers were taking statements from three young women across from a cordon set up around the house, and a command tent had also been erected.

Police are contacting the woman's family, who are spread throughout Australasia.