A man shot dead by police outside a regional NSW medical centre has been revealed as having a long history of mental illness, and had previously posed as a lawyer.

Alexander Stuart Pinnock died after a stand-off with police at a clinic in Nowra, on the NSW South Coast, on Wednesday afternoon. 

The 34-year-old reportedly pulled out a firearm about 1pm, prompting staff members to call police and escape the Junction St building.

Mr Pinnock came out of the clinic about 90 minutes later, confronting officers and brandishing what police believe was a semi-automatic Glock pistol at them.

He then picked up a ballistic shield that was dropped by retreating officers, police said.

Mr Pinnock was shot before being treated by on-hand paramedics and police, but he died at the scene.

NSW Police Assistant Commissioner Peter Cotter said the 34-year-old – who was known to the medical centre and staff – became agitated while speaking with a doctor and produced a firearm unprovoked.

“He’s fallen upon troubled psychological times, I’m not sure for exactly how long but certainly in recent times that’s flared up,” Mr Cotter told Sydney radio 2GB on Thursday.

“Unfortunately and tragically he turned up to that doctor surgery and he was the one that was the catalyst for all the actions that unfortunately happened thereafter.”

Staff contacted police who established a perimeter around the building and started negotiations.

Police said up to four people who were in the clinic escaped soon after the stand-off began and were not physically harmed.

Officers spoke with the gunman from outside the building before he emerged, brandishing the firearm.

Mr Pinnock was shot multiple times after raising the weapon at police, Mr Cotter said.

Footage filmed from a nearby business showed armed officers in protective gear outside the medical centre talking to a man at the entrance.

A bystander can be heard saying: “Oh my God they shot him, oh my God they shot him.”

Mr Cotter defended the actions of police but said any investigation would review the proportionality of the response.

“Police turned up (and) they did their very best to assess the situation,” he said.

“They were threatened, they took action (and) that will be reviewed, investigated and scrutinised.”

Mr Pinnock did not have an extensive criminal record and was known to police largely through previous medical and psychological episodes that required intervention.

But last year he pleaded guilty to six offences brought against him by the Law Society of NSW after he was caught practising without a licence under the alias Alec Stuart.

The Victorian Legal Services Board also issued a statement in May warning that Mr Pinnock was not a registered practitioner and could not engage in any type of medical practice.

In an interview with Nine’s A Current Affair in April, Mr Pinnock said he was diagnosed with schizophrenia in 2014 and had recently been experiencing psychosis.

“Having schizophrenia, the definition of it is not really being aware of truth from reality,” he said.

A critical incident team from the police homicide squad is investigating the circumstances leading up to the death. It will be subject to an independent review.

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