More police activated to curb tension in Sydney's west

The stabbing - which has since been declared an act of terrorism - triggered the riot outside the Christ the Good Shepherd Church in Wakeley leaving dozens of police officers injured.

Police quelled a riot outside the church as people clashed with officers and each other. (Paul Braven/AAP PHOTOS)

On Wednesday night, police confirmed their first arrest, of a 19-year-old Doonside man, over the public order incident, with many more arrests expected.

The arrested man has been charged with riot, affray and destroying/damaging property during public disorder and been refused bail to appear at Blacktown Local Court on Thursday.

More than 70 additional police officers have been deployed in Sydney's west to conduct high-visibility patrols.

Another 32 investigators have been assigned to investigate the riot which saw some worshippers try to gain access to the attacker, who was being held inside the place of worship at the time.

The ensuing chaos left 47 police officers injured and dozens of vehicles vandalised, while several paramedics were forced to shelter in the church.

Investigators are collating evidence including mobile phone and CCTV vision to identify those involved. 

Police Minister Yasmin Catley said everyone had the right to go about their daily lives and practice their faith free from violence or intimidation.

"These extra boots on the ground will help provide calm and safety at a time when it's needed most," she said in a statement on Wednesday.

Fairfield MP David Saliba said the additional police resources will facilitate broader government measures to "promote peace and harmony in Fairfield and surrounding areas."

A 16-year-old boy remains in hospital under police guard after he was arrested over the church attack. 

Police are treating the knife attack as a terrorist act after the teenager allegedly made comments in Arabic that referred to insults against "my Prophet" before the stabbing.