Police say a man has been arrested after reportedly stabbing a bishop and churchgoers in Sydney. There are no life-threatening injuries reported.

It occurred during a televised service on Monday evening, police said.

A video on social media shows a man dressed in black approaching a cleric identified as the bishop at Christ the Good Shepherd in suburban Wakely and appearing to stab him repeatedly in the head and upper body.

Members of the congregation are seen screaming and rushing to the bishop's aid.

NSW Ambulance said said they had treated a man in his 50s for multiple cuts and taken him to a hospital, and three others were being treated for one or more cuts at the scene.

"A large police response is underway and the public is urged to avoid the area," police said.

Australians are still in shock after a lone assailant stabbed six people to death in a busy Sydney shopping mall on Saturday and injured more than a dozen others.