Police shoot dead 16yo armed with a knife in Perth, premier ...

Police have shot dead a 16-year-old boy who stabbed another man with a kitchen knife in Perth, saying the teenager was "radicalised" online.

WA Police said they received an emergency call just after 10pm on Saturday from a teen saying he was going to commit acts of violence.

A second triple-0 call was made a short time later after reports a man had been stabbed in the car park of a Bunnings store in Willetton, in Perth's southern suburbs.

Police Commissioner Col Blanch said when they arrived, they found a 16-year-old armed with a large kitchen knife.

Commissioner Blanch said the boy lunged at officers with the knife and was shot.

He died a short time later in hospital.

The police commissioner and WA Premier Roger Cook held a press conference on Sunday morning and described the incident as "extremely confronting".

They said the boy was "running around a car park, armed with a knife" before stabbing another man not known to him in the back, in what appeared to be a random attack.

"They [WA police] exited their vehicle and were confronted with a male alone with a large kitchen knife," Commissioner Blanch said.

"Two officers drew their tasers and one of the officers drew his firearm.

"They challenged the male to put down the knife, which he did not."

Police have now left the scene at the Bunnings car park in Willetton.(ABC News: Tabarak Al Jrood)

Commissioner Blanch said the body-cam footage he watched showed the 16-year-old rushing one of the officers with the knife before both officers deployed their tasers.

"Both of them didn't have the full desired effect, and the male continued to advance on the third officer with the firearm, who fired a single shot and fatally wounded the male."

A pool of blood on the car park bitumen on Sunday morning was the only remaining clue something had happened overnight, as business continued as usual.

Mr Cook said there were indications the boy had been radicalised online.

"But I want to reassure the community at this stage it appears that he acted solely and alone," Mr Cook said.

Roger Cook addresses the media at a press conference on Sunday morning in the wake of the Willetton attack.(ABC News: Rebecca Trigger)

"Members of the WA Muslim community, who were concerned by his behaviour, contacted police prior to the incident and I thank them for their help."

It was also said the boy's family was cooperating with police.

Commissioner Blanch said the incident was not being labelled as a terrorist attack at this stage.

"It certainly has the hallmarks of one [but] the reason why I would declare it as a terrorist act going forward — it's about timing," Commissioner Blanch said.

"If I need extra capability, particularly from the Commonwealth, sometimes you'll see terrorist acts being declared very early.

"I believe this is a person acting alone … I don't need additional capability at this time, whilst it meets the criteria, or at least the definition.

"That's something that we can work towards as we find out more information from the motivations behind this."

Commissioner Blanch said the teen was known to police and was part of a program designed to help individuals at risk of being radicalised.

He said it was a support program focused on individuals who expressed ideologies that were of concern to the community but "they may not be committing any crimes".

"We are dealing with complex issues with this 16-year-old male — both mental health issues but also online radicalisation issues," he said.

"[The program is] for those that are exhibiting behaviours that might be religious or issues motivated.

"This 16-year-old Caucasian male was part of that program."

Prime Minister Anthony Albanese thanked police for acting swiftly to contain the situation.

"I have also received a briefing on the situation by the ASIO Director-General and the AFP Commissioner, and I'm advised there is no ongoing threat to the community on the information available," Mr Albanese said in a statement.

"We are a peace-loving nation and there is no place for violent extremism in Australia."

The man who was stabbed by the boy, aged in his 30s, was recovering in Royal Perth Hospital in a serious but stable condition.

It is believed he sustained a two-centimetre stab wound to the back that may have punctured a lung. 

An urgent meeting of community faith leaders and authorities is set to be held on Sunday afternoon in Perth.