A man wanted for domestic violence and weapons offences was behind a fatal overnight siege at a home west of the Blue Mountains, police say.

The 29-year-old was found dead inside a home near Lithgow after a 21-hour siege involving an exchange of gunfire and lengthy negotiations.

His fatal wound was believed to be self-inflicted.

Investigators are yet to speak to a 20-year-old woman who was also at the property during the siege.

She surrendered herself and the man’s rifle about 8.50am on Monday, leading police to find the man dead.

The woman was transferred to hospital for an assessment but Assistant Commissioner Scott Tanner declined to state whether she was injured or subjected to threats inside the property.

“Until we have a time to speak with that female, at this stage we’re only speculating on what the circumstances were with her in the house,” he told reporters on Monday.

NSW Police had been unaware of the man’s identity when officers responded on Sunday to reports of the pair arguing outside the Bowenfels home.

Officers spoke briefly with the pair from a distance before the couple retreated inside, locked the doors and refused to come out.

Inquiries through the negotiation unit established the identities of the man and woman, Mr Tanner said.

The man had been wanted for serious domestic violence and firearm matters dating back to 2021.

As negotiations continued, police locked down neighbouring streets, stopped trains running between Lithgow and Bathurst and called in the Tactical Operations Unit.

Gunfire was exchanged between one of the occupants and the police surrounding the property about 4.20pm, though no injuries were reported.

Mr Tanner said the exact number of shots fired each way would be known once the crime scene was completely examined.

The 20-year-old woman is helping police with their inquiries and out-of-area police have launched a critical incident investigation.

Those investigations will be subject to an independent review, including by the Law Enforcement Conduct Commission.

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