PM Anthony Albanese convenes security cabinet meeting over Sydney church 'terrorist act'

Prime Minister Anthony Albanese has convened a meeting of the national security subcommittee after an alleged terrorist act in Sydney's south-west on Monday night.

Bishop Mar Mari Emmanuel sustained lacerations to his head after being lunged at during a mass service at Assyrian Orthodox Church Christ The Good Shepherd Church in Wakeley that was being broadcast online.

The 53-year-old underwent surgery and a 39-year-old man also sustained cuts and a shoulder injury while attempting to intervene, NSW police say.

A 16-year-old who police say was known but not "well-known" to them was arrested at the scene after being held down by members of the church, and was also hospitalised for finger injuries.

New South Wales Police Commissioner Karen Webb declared the stabbing a "terrorist incident" early on Tuesday morning in a move supported by ASIO.

"This is a major and serious criminal investigation, it is crucial that NSW police are able to devote their resources and intelligence as well as officers to the investigation of this crime," Premier Chris Minns said.

Albanese, Deputy Prime Minster Richard Marles, Foreign Minister Penny Wong and other senior cabinet members, alongside heads of the ADF (Australia Defence Force) and ASIO (Australian Security Intelligence Organisation), met in Canberra on Tuesday.

At least two police officers were injured after crowds who had assembled after the incident smashed police cars in violent scenes.

Commissioner Webb said an "uncontrolled" crowd surge of between 50 to 500 people formed after the stabbing, against "police officers ... doing their job".

"We've had police injured and taken to hospital overnight, and we've had many, many police vehicles damaged ... and 10 are unusable," she said.

"Police attended the incident at Wakeley last night to assist the community in response to calls for assistance and the crowd turned on police."

Prime minister asks public to let police do their job

Albanese said there was no place for violence in Australia.

"I understand that people are feeling uneasy, and that's understandable ... given the atrocity that occurred on Saturday and then this incident last night," he said.

"I discussed this with Premier Minns this morning as well, and part of us standing up here is to reassure the public that the authorities are doing their work.

"I have every faith in the New South Wales police, in the Australian Federal Police, in our security agencies, to do their work."

He also called on the public to not "impede and injure police doing their duty".

"People should not take the law into their own hands but should allow our police and our security agencies, to do their job."

Church attack did 'appear to be religiously motivated'

The prime minister said he had been briefed by Australian Federal Police (AFP) Commissioner Reece Kershaw and by the national intelligence agency chief Mike Burgess.

Burgess said the attack did "appear to be religiously motivated" but said that lines of investigation were ongoing.

"At the same time, our job is to look at individuals connected with the attacker to assure ourselves there's no-one else in the community with similar intent," he said.

"At this stage, we have no indications of that. But it's prudent that we do this to determine there are no threats or immediate threats to security."

Referring to the case of a man being wrongly identified by media organisations and people online as the culprit in the weekend's Bondi Junction stabbing attack, which killed six and injured many others, the prime minister said people should respond with calm.

"We remain concerned about the role of social media, including the publication of videos that can be very harmful, particularly for younger people who have access," Albanese said.

"I think that on Saturday we saw some of the best of human character at the same time as we saw such devastating tragedy."

- This story was first published by the ABC.