Loading NSW Police Commissioner Mick Fuller said the offender unleashed "terrifying carnage" in what appeared to be a random attack. He called those who tackled the suspect to the ground "highest order heroes" as the man "was clearly dangerous and had motive". Mr Fuller said the man was in possession of ideological material related to terrorism, but stressed it was not being treated as a terrorist incident at this stage. "He is by definition at the moment a lone actor," Mr Fuller said. "Information was found on him that would suggest he had some ideologies related to terrorism... but he has no apparent links to other terrorist organisations," Mr Fuller said."It is not currently classed as a terrorist incident... As investigation continues we will reassess that.

"The response by members of the community ... was first-rate. Unfortunately, we have lost the life of an innocent person. We will leave no stone unturned." Footage shows the alleged attacker yelling "Allahu Akbar", however Mr Fuller said the suspect had a history of mental health issues the police were aware of. "At the end of the day this is a horrendous crime and he should pay for that."

Motorists were urged to avoid Sydney’s CBD in the evening because of "extremely heavy" traffic in the area, with roads closed and several bus routes affected. Loading Earlier, Detective Superintendent Gavin Wood praised the "brave people" who approached the suspect and performed a citizen's arrest. They intervened in the face of "incredible danger”. "They were brave, and I can only use that word seriously, they were significantly brave people to approach a person of the mindset of obviously what this person did, with clear evidence of a stabbing previously. "These people are heroes, and I want to acknowledge that. These people, these members of the public going about their daily business, have jumped into a situation which was extremely dangerous, extremely hostile."

Footage shows the alleged attacker yelling "Allahu Akbar", and Detective Superintendent Wood said it would be investigated. "That is something that has been reported to me, but we certainly haven’t captured that as an evidentiary base. That’s part of our investigation, and we’ll be using that evidence as we move forward.” Screenshot from 7 News showing the citizen's arrest of man who allegedly tried to stab people in Sydney. Credit:7 News The Clarence Street apartment block where the woman's body was found about 3.15pm was still blocked off to residents three hours later as police examined the crime scene. Police say frustrated residents of the unit block will have to remain outside their homes for several hours as forensic police continue to examine the crime scene and work into the night.

Prime Minister Scott Morrison called the attack "deeply concerning". "The attacker is now in police custody following the brave actions of those who were present at the scene and were able to able to restrain him," he said via Twitter. "Our thoughts are with all those who have been impacted by this violent attack."

Speaking in London, Premier Gladys Berejiklian said she was being kept updated on the incident and offered her condolences to the victims. "Our thoughts and prayers are obviously with the deceased and the victims of this horrific time,” Ms Berejiklian said. Loading Replay Replay video Play video Play video "I also want to acknowledge the very brave passers by who obviously tried to intervene and our thoughts are with the victims and everyone who witnessed this horrific incident.” A British man who helped to chase and tackle the alleged stabber says he didn't think twice because he sees Australia as his "new home".

"We just tried to get down as quick as we could ... You don't think … you just kind of react really, it was surreal, very, very surreal," said Lee Cuthbert, 29, who was working in his York Street office when the attack began. Loading One witness was having a coffee at a cafe on Clarence Street when she saw dozens of people running from York Street, and heard shouting. "I looked up and saw two men heading towards me, the one in front tripped over and looked behind him. He seemed to be running from the second man, and he fell over and people were picking him up. "Then the second one fell to the ground too. He was being pursued by a man in uniform – a firefighter I think, navy blue overalls – who had a crowbar.

"Then they had the man on the ground and they put a chair from the cafe over him to keep him down and people started to cluster around. "It was about 10 minutes until police came. It was just regular people holding him down, including the fireman." Jack Huddo wrote on Twitter: "A random dude just started stabbing people in the city right outside where we were having lunch. I saw people running so I ran towards him with a few other guys." A woman is taken from Hotel CBD on the corner of King and York streets. Credit:AAP "He ran all the way back to near my work where a lot of others had cornered him for the police," he said.