A well-known ultra-conservative bishop has been stabbed in Sydney's second knife attack in a matter of days.
Worshippers were also injured in the crime, which was broadcast on a livestream of the service.
Police are investigating the crime as "a terrorist act".
A teenager has been taken into custody by police.
Here's what we know.
Who is church leader Bishop Mar Mari Emmanuel?
Bishop Mari Mari Emmanuel was stabbed along with several worshippers in the middle of a service at Christ The Good Shepherd Church in Wakeley on Monday night.
He is a prominent leader of an ultra-conservative sect of the Assyrian Orthodox faith who became popular during the COVID-19 pandemic for being critical of lockdowns and vaccines, according to The Telegraph.
The bishop called lockdowns "mass slavery" and said people's immune systems would fight off the virus.
He's also a preacher known for his anti-LGBTQ views.
The leader has a massive online audience, with 17,000 followers on Facebook and 200,000 subscribers on YouTube. Videos he has posted to TikTok have been viewed millions of times.
Who was the knifeman?
A 15-year-old boy has been arrested after allegedly stabbing Bishop Mari Mari Emmanuel in the attack.
The service was being broadcast on a livestream which shows the teenager, wearing a black hoodie, walking up and lunging at the bishop and stabbing him multiple times in the head and upper body.
Four other people were wounded as members of the congregation rushed to the bishop's aid.
The boy stabber suffered "quite severe" hand injuries and was "fairly upset and fairly distraught", Acting Assistant Commissioner Andrew Holland said according to Nine News.
It's unclear if the motive for the attack is linked to the bishop's views.
What happened outside the church after the attack?
Following the stabbing, the teen was taken by police to a secure area of the church.
This sparked an angry gathering of church supporters outside the building.
Hundreds of police were deployed to the area, holding up shields to protect themselves from rioters.
At a Tuesday press conference, NSW Commissioner Karen Webb told media the crowd surged from 50 to hundreds very quickly.
"It was very uncontrolled for a period of time," she said.
"In fact, for a couple of hours, resources from all across Sydney were deployed and called... into respond to assist those police on the ground that were calling for help."
Premier Chris Minns said thousands of police officers were deployed as the incident unfolded, triggering the riot outside.
"They deployed resources to other religious organisations and structures throughout Western Sydney in order to avoid retaliation or tit-for-tat violence," he said.
