Three British men are being hailed as heroes after confronting a knife-wielding man who killed one woman and wounded another in downtown Sydney before trying to stab others Tuesday while yelling "Allahu akbar," according to police and witnesses.

New South Wales Police Commissioner Michael Fuller said authorities have not labeled the stabbing rampage as an act of terrorism, but the 21-year-old suspect with a history of mental illness had collected information online about mass killings in North America and New Zealand.

"He is, by definition, at the moment, a lone actor. Information was found on him that would suggest he has some ideologies in relation to terrorism, but he has no links to terrorism," Fuller told reporters. "There was certainly information found on him about other crimes of mass casualties and mass deaths around the world."

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The incident unfolded around 2 p.m. near a busy intersection in Australia's largest city when the man carrying a 12-inch knife attempted to stab multiple people, according to police. Witnesses said the man was attempting to attack people while yelling "Allahu akbar" -- "God is the greatest" in Arabic -- before he was restrained by bystanders. Video taken by witnesses also showed him shouting the phrase.

Fuller, who described the weapon as a butcher's knife, said a 41-year-old woman with a stab wound on her back was taken to a hospital in stable condition. The body of a 21-year-old woman was later discovered in a nearby fourth-floor apartment, according to police.

"A number of members of the public physically restrained the offender," Police Superintendent Gavin Wood said. "I want to acknowledge those members of the public who got involved. They were significantly brave people."

Video showed the man running through an intersection, jumping on a car while waving a knife before a group of men pinned the suspect to the pavement on his back with a plastic milk crate over his head and two chairs over his body.

The group of British men from Manchester who pinned down the man -- Lee Cuthbert, Paul O'Shaughnessy and his brother Luke -- said they were working in their recruitment company office when they heard shouting on the street, looked out and saw a Caucasian man screaming "extremist" words, and gave chase.

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"He had a knife, it was covered in blood. He kept saying something in Arabic, he was clearly under the influence of something," Paul O'Shaughnessy said. "My brother Luke managed to keep him pinned down until the police arrived. My brother put a crate and a chair to keep him pinned down. He didn't show any remorse at all."

New South Wales Police Minister praised the men's actions.

"The city, tonight, celebrates three brand-new heroes," he said. "And I think it would only be appropriate for the commissioner and I to thank those three individual citizens who have acted well and truly beyond the call of any citizen in bringing this offender to bear."

Wood said it appeared that the attack was unprovoked. The man "attempted to stab multiple people. Those attempts, thankfully, were unsuccessful," Wood said.

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A witness told reporters that the man was screaming comments about religion, before yelling to police that he wanted to be shot, Sky News reported.

Fuller said the assailant had a "history of mental health," and that the assailant would be charged.

Prime Minister Scott Morrison said on Twitter that the violence was "deeply concerning" and praised the people who restrained the assailant.

The Associated Press contributed to this report.