Police have cordoned off several streets in central Sydney as they respond to reports of a man armed with a knife.
Local media reported multiple possible stabbings in the area around King and Clarence streets, though this was not immediately confirmed by officials.
A witness told Reuters she had seen a man armed with a knife bleeding and running through the street outside a Subway store. "The cops are here and they blocked the road right now, so we can't go outside," she said.
Some videos posted online appeared to show a man running through the city centre brandishing a knife and threatening several people before he is eventually tackled to the ground.
Other images reportedly showed the man being pinned down with a milk crate before police arrived on the scene to take him away. A Sky News reporter said the man was heard shouting "shoot me" at the police.