A 15-year-old boy has been arrested in Sydney for a suspected 'terrorist act' after a knife attack during a livestream at an Assyrian church.

The bishop was stabbed multiple times by the teenager, who was known to police and had made comments during the attack.

Following the incident, street violence ensued, with police officers injured, vehicles damaged, and the attacker and a senior priest hospitalized in stable condition.

A large crowd outside the church became violent, leading to over 100 police officers and 30 police vehicles responding to the public order incident.

The suspect is under hospital police guard, has undergone surgery, is cooperating with authorities, and arrests related to the riot are anticipated.

Australian authorities have established a separate strike force to investigate the riot and designated the stabbing as a terrorist attack.

Prime Minister and religious leaders call for unity and calm, condemning violent extremism, while local federal member Dai Le asks for increased police resources.