A Christian bishop and three churchgoers have been stabbed by a man during a televised service in western Sydney.
Police said a large police response was under way and a man was arrested in Wakeley on Monday night following reports of multiple people being stabbed.
"Officers arrested a male and he is assisting police with inquiries," police said in a statement.
Video circulating on social media shows a man dressed in black approaching a man named as Mar Mari Emmanuel, the bishop at Christ the Good Shepherd Church.
The man is seen stabbing the Assyrian Orthodox bishop multiple times to the head and upper body at the altar as parishioners screamed and ran to the cleric's aid.
The man remains in police custody.
NSW Ambulance said they were called to the church about 7.15pm and sent multiple paramedics to the scene.
A spokesman said they had treated a man in his 50s for multiple cuts before taking him to Liverpool Hospital.
A man his 30s was also treated for lacerations and taken to hospital.
A man in his 20s was being treated for a cut to his hand and a man in his 60s treated for a laceration to his arm at the scene.
The attack comes two days after Sydney and the nation was left reeling by a stabbing rampage at Westfield Bondi Junction that killed six people.
Joel Cauchi was shot dead during the rampage on Saturday, which also injured seven people including a baby girl.