The 15-year-old suspect, whose identity has not been released, allegedly shouted "Allahu Akbar" before lunging at Assyrian orthodox Bishop Mar Mari Emmanuel with a knife, leaving him with non-life threatening injuries.
"At 1:35 am this morning," NSW Police Commissioner Karen Webb told reporters, "after consideration of all the material, I declared that it was a terrorist incident."
She went on to explain that a referral was made and agreed to by the the Joint Counterterrorism Investigation Team to work with state and federal law enforcement agencies, and that a task force had been established.
Webb urged people to stand back and allow police to do their jobs, scolding those who gathered outside the church calling for the suspect to be brought to them so they could deal with him themselves. Members of the group, who suggested an "eye for an eye" was the only acceptable solution, damaged numerous police cars and allegedly assaulted officers as they tried to tend to those in need of assistance.
"There is no such thing in Australia as taking the law into your own hands," NSW Premier Chris Minns added. "You will be met by the full force of the law if there's any attempts of tit-for-tat violence in Sydney over the coming days ... Every religious leader representing communities across western Sydney has said don't do it."
Footage of the incident shows a man walking up to the bishop mid-mass before violently attacking him. The suspect continued to stab Emmanuel even after he fell to the floor.
While being subdued and berated by parishioners, the suspect could be seen smiling about what he'd done.
