Australian police said that a knife assault on an Assyrian church bishop and several followers in Sydney was a terrorist act motivated by suspected religious fanaticism.

At least four people were injured in the incident, including Bishop Mar Mari Emmanuel of the Assyrian Christ The Good Shepherd Church, who was lunged at with a knife during a live-streamed liturgy on Monday.

PHOTO | COURTESY Police at the crime scene

The attack in the western Sydney suburb of Wakeley sparked fights outside the church between police and an angry throng of the bishop's supporters, who demanded that the perpetrator be handed up to them.

Police apprehended a male teenager at the site and had to restrain him.

PHOTO | COURTESY Police at the crime scene

"We believe there are elements that are satisfied in terms of religious motivated extremism," New South Wales state Police Commissioner Karen Webb said during a press conference.

"After consideration of all the material, I declared that it was a terrorist incident."

Police believe there was premeditation since the male attacker arrived at the church, which was distant from his house, carrying a knife. However, Webb stated that authorities think the attacker acted alone at this inquiry stage.

PHOTO | COURTESY Police at the crime scene

 Christ the Good Shepherd Church described the attack as an isolated event and said it was waiting for authorities to investigate the attacker's motive.

"The Church denounces retaliation of any kind," the statement added.

Authorities encouraged people not to take the law into their own hands.

"You will be met by the full force of the law if there's any attempt for tit-for-tat violence in Sydney over the coming days," New South Wales state Premier Chris Minns told reporters.