A man armed with a knife has been shot dead by a police officer during a "violent struggle" at a Perth home in which two officers were also injured.
Police were called to Gosnells in Perth's southeast around 1am on Monday after reports of a dispute between the two male residents.
WA Police Deputy Commissioner Col Blanch said four officers attended the home and spoke to one of the men, aged in his 30s, before he armed himself with a knife.
In the struggle that ensued, one officer suffered a knife wound to the arm and another injured his hand.
Police deployed capsicum spray and a Taser before an officer drew his gun and fired two or three shots, with the man declared dead around 1.40am.
"There was quite a violent struggle prior to that, and police were doing everything they could to subdue the male," Deputy Commissioner Blanch told reporters.
Homicide detectives are investigating the incident with oversight from the police internal affairs unit and the Corruption and Crime Commission.
It has also been referred to the coroner and an inquest will eventually be held.
Mr Blanch said footage from body-worn cameras would be reviewed as part of the probe.
The injured officers were taken to Armadale Hospital for treatment but have since been discharged.
It is not yet clear whether all of the shots fired had hit the man or which officers had deployed the Taser and capsicum spray, he said.
The officers involved will take critical incident leave and be provided with welfare support.
"No officer expects to go to work and have this occur to them," Mr Blanch said.
"So that's something that they will need to work through themselves and I support those officers in getting that support."
The incident comes days after a first-class constable who shot dead an Indigenous woman on a suburban street in Geraldton in 2019 was acquitted of her murder.
The WA Supreme Court jury on Friday also found the officer not guilty of the lesser charge of manslaughter.
The victim of the Gosnells shooting is not believed to be Indigenous. It is not yet clear whether he was known to police.
Responding to the incident, Premier Mark McGowan said he had been advised the officers' lives had been in "grave danger".
"Obviously it's a very distressing situation," he told reporters.
"The police do a very difficult job in sometimes very hostile circumstances and I'm sure we're all thinking of them."
WA Police Union acting president Mick Kelly said officers were trained to constantly reassess risk levels and use the appropriate force in response.
"We don't want our members in that position. We try to have people comply with instructions and drop weapons so they can be treated in hospital to get the appropriate care," he told Perth radio 6PR.
Australian Associated Press