There were signs he was radicalised online and concerned members of the Muslim community had called police before the attack in Perth, said state authorities.

The attack - at about 10pm on Saturday - in the suburb of Willetton, had the "hallmarks" of terrorism, police said.

The boy first called police himself shortly before the attack to say he was going to commit violence, but didn't say where or who he was, said Sky News Australia correspondent Crystal Wu.

A 30-year-old man was then stabbed in the back with a kitchen knife and three police officers were deployed, Wu said.

Two officers drew Tasers, and the other a firearm, as they ordered the teenager to put down his weapon.

However, he refused, so he was shot.

Local reports indicate the boy was known to police and suffered from both "mental health and radicalisation issues" and was in a deradicalisation programme.

Western Australia Premier Roger Cook said in a televised news conference that "at this stage it appears that he acted solely and alone".

The victim is stable in hospital, authorities said.

Prime Minister Anthony Albanese said he had been briefed on the incident by police and intelligence agencies, which advised there was no ongoing threat.

"We are a peace-loving nation and there is no place for violent extremism in Australia," Mr Albanese wrote on X.

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The incident comes after New South Wales police last month charged several boys with terrorism-related offences in
investigations following the stabbing of an Assyrian Christian bishop while he was giving a live-streamed sermon in Sydney.

The attack on the bishop came only days after a deadly mass stabbing in the Sydney beachside suburb of Bondi that claimed the lives of six people.