Young worshippers at a Hillsong church have been injured and a security guard knocked out after a brawl outside one of the church's Sydney campuses.

An argument with a group of young men escalated into violence, according to  7 News. Security guard Ashil Nada, 33, was treated in an ambulance after he was knocked unconscious by a so-called 'coward punch' in the back of the head. He was trying to protect the Hillsong worshippers when they were targeted.

The campus pastor, Christian Jeyaratnam, said members were praying for Nada.

'He is a really great guy and has served as part of the security team here for many years... and our thoughts are really with him,' he said.

He said a passer-by in a car 'recognised one person that was walking home and what ensued was some kind of scuffle'. He said he did not believe it was a religiously-motivated attack.

Youth leader Caleb Matenga told 7 News he was waiting for three teenagers to be picked up when they were attacked by a group of random men. Two Hillsong worshippers, a 21-year-old and an 18-year-old, were hit in the face.

The campus attracts hundreds of people for its weekly service, but neighbours told 7 News the events were sometimes rowdy and that fights spilled onto the street.

Jeyaratnam said: 'Every young person has baggage and so we'll always have security so the young people here are safe.'

Police are continuing their search for the men involved.