The Perth Muslim community had raised concerns over the behaviour of a "radicalised" 16-year-old high school student before he allegedly stabbed a man in a car park.
Police said the boy stabbed a stranger in the back, leaving him hospitalised in a serious condition, outside Bunnings on High Road in Willetton after 10pm yesterday.
Police fatally shot the boy, who they said was armed with a 30-centimetre kitchen knife, in a standoff.
The teenager had been a student at Rossmoyne Senior High School.
In an email to parents and carers, school principal Alan Brown confirmed he died in the incident.
"We acknowledge and respect the family's right to privacy ... Our thoughts are with them and their friends during this difficult time," he wrote.
The WA Department of Education said the school would provide additional support for students, who were trying to deal with an unthinkable tragedy.
Police Commissioner Col Blanch said the boy was Caucasian, had converted to Islam and had "mental health issues and radicalisation issues".
He said the boy had been attending a program to combat extreme online violence extremism - in which seven youths and almost a dozen adults were being monitored.
Members of the Muslim community had also contacted police and raised concerns over his behaviour prior to last night's alleged attack, Premier Roger Cook said.
"There are indications he had been radicalised online," he said.
Syed Wadood Janud, Imam of Perth's largest mosque Nasir Mosque, condemned the alleged attack "in the harshest terms possible", saying it went against the teachings of the religion.
"We would also like to mention that Islam has nothing to do with any acts of violence that are committed in its name. Islam is a religion that literally means peace," he said at a press conference today.
Blanch said the teen had phoned triple zero about 10.10pm informing them he planned to commit "acts of violence".
He said a second triple zero call was made by a member of the public who allegedly witnessed the teen running around the car park wielding a knife.
"When he was chasing the police car around, he was holding (the knife) at his waist area and when he was running toward the police car obviously he was holding it up in the air," witness John Chi told 9News.
Police said they tried to get the boy to drop the knife and deployed two Tasers when he did not comply.
"The male continued to advance on the third officer with the firearm, who fired a single shot and fatally wounded the male," Blanch said.
The police commissioner defended the police officer's actions, saying he acted professionally.
"I have seen the body-worn video. I am comfortable with the police approach, they have done their job," he said.
The victim, aged in his 30s, is now in a stable condition in hospital.
Authorities assured the community the teenager acted alone and there was no ongoing threat to the public.
In response to the incident, Cook called an emergency meeting with ministers, the police commissioner and multi-faith leaders, which was held today.
In a statement about the incident today, Prime Minister Anthony Albanese said there was "no place for violent extremism in Australia".
"My thoughts are with those who have been affected by the incident," he said.
"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."
