A knife attack during a ceremony at an Assyrian church in Sydney injured a bishop, Australian police said on Tuesday, in a suspected religious extremist terror attack.

At least four people were injured in an attack on Monday during a livestreamed service in Wakeley, in Sydney’s western suburbs, including Bishop Mar Mari Emmanuel of the Assyrian Church of Christ the Good Shepherd.

The incident sparked clashes outside the church between police and angry followers of the bishop, who demanded that the attacker be handed over to them.

On Monday, police arrested a male teenager at the scene and were forced to detain him inside the church as a large number of worshipers gathered outside.

“We believe there are elements of religious extremism that are desirable,” New South Wales Police Commissioner Karen Webber told a news conference.

“Having considered all the material, I declare this to be a terrorist incident.”

Police said there was “a degree of premeditation” when the male attacker went to a church far from his home armed with a knife. But Weber said police in the early stages of the investigation believed the attacker acted alone.

Emergency services said they treated about 30 people after the clashes outside the church, with seven injured and taken to hospital. Weber said several police officers were injured and hospitalized and 20 police vehicles were damaged.

It was the second major knife attack in Australia’s most populous city in three days, after six people were killed and 12 injured in a knife attack at a beachfront shopping center in the Bondi area on Saturday.

Video footage shows Bishop Emmanuel, whose live-streamed sermons have captivated a global audience, speaking during an evening service when a man lunged at him with a knife.

Videos of the bishop’s sermons have received hundreds of thousands of views on YouTube and TikTok. He became known for his hard-line views during the pandemic, when he described the coronavirus lockdown as “mass slavery,” according to media reports at the time.

NSW Premier Chris Mining urged people not to take the law into their own hands.

“If there is any tit-for-tat violence in Sydney over the next few days, you will be met with the full force of the law,” Mings told reporters.