Three Britons have been hailed as "heroes" by police after they helped detain a knifeman linked to the death of a 21-year-old woman in Sydney.
Lee Cuthbert, Paul O'Shaughnessy and Luke O'Shaughnessy, all from Manchester, were working in the area when they heard the man attempting to stab several people outside.
They described the moment they apprehended the suspect as being likely down to "instinct", with dramatic eyewitness footage appearing to show a young man being pinned to the floor with chairs and a milk crate.
Paul O'Shaughnessy, told reporters: "He had a balaclava on, he was wielding a knife with blood on it,
"And we were like: 'Wow, what is going on here?'
"We went down the escalator and continued to chase the guy where other people were going away because obviously he was wielding a knife.
"I don't know whether it was an instinct thing or not what, but we was like, right, we've got to try and restrain this guy from doing any more.
"My brother and I just ran across here, these boys followed, and we managed to get a grip with him and another guy.
"We've got a grip of him and restrained him fully, and then just waited for the cops to come. He's got blood all over him."
Police confirmed they were investigating allegations the suspect yelled "Allahu akbar", or "God is great", but are not treating it as a terror incident.
Police said the suspect - a 21-year-old man from Maryong in New South Wales - attempted to stab several people in the Australian city, at around 6.15am BST (3.15pm local time) before being arrested.
A woman was found dead in a building nearby and police were investigating if the earlier stabbing at a hotel on the corner of Clarence and King streets was linked to the street attacks.
New South Wales Police Superintendent Gavin Wood, speaking to reporters near the scene, said: "A number of members of the public actually physically restrained the offender.
"And I want to acknowledge those people, those members of the public who got involved. They are brave, and I can only use that word seriously.
"They are significantly brave people. They approach the person ... with clear evidence of a stabbing previously. These people are heroes, and I want to acknowledge that.
"These members of the public going about their day-to-day business have jumped into a situation which was extremely dangerous, extremely hostile, and they have brought a person - who we will be alleging stabbed an innocent person for no specific reason - into custody and allowed us to do our job."
Police said a second woman in hospital was not in a life-threatening condition, while a third woman was said to have a minor injury to her hand.
Witness Brodie Smith said on Twitter: "Saw the attacker drop his knife in the street on York St.
"I realised he had a knife and shouted about it, and he picked it up and ran.
"Then I saw all these people chasing him back the other way... and then this. I can't imagine if he had a gun. We'd all be dead."
Australian Prime Minister Scott Morrison commended the bystanders for intervening.
He posted on Twitter: "The violent attack that took place in Sydney this afternoon is deeply concerning.
"The attacker is now in police custody following the brave actions of those who were present at the scene and able to restrain him.
"The motivation for this attack has not yet been determined as police are continuing with their enquiries.
"Our thoughts are with all of those who have been impacted by this violent attack."
Footage posted online appears to show a suspect standing on a vehicle roof in the middle of a busy city street, holding a knife aloft and shouting before he was later apprehended.
The unnamed driver, an Uber driver, was carrying an elderly couple at the time.
He said he saw that traffic had stopped and people were running, telling Nine News Sydney: "All of a sudden this guy appeared with a knife in his hand covered in blood, down the front shirt, and next thing I thought OK well obviously I can't go through all these cars.
"As I'm thinking about doing something the guy jumps on the front of the car which was on the bonnet over here and then he goes up to the very top."
He added: "I froze for probably a split second but then I thought I'm hoping that he's not covered in any explosives or anything, so I quickly accelerated so he can get off the car."
He said he drove left and then took a right turn where he could see the suspect again being chased by police and public.
"He was fearless. He was completely fearless," he said, adding that he had "a big scary knife" in his hand.