Queensland police are scouring the scene where British backpacker Mia Ayliffe-Chung was murdered in a frenzied knife attack, amid reports her alleged killer may have been driven by a "delusional obsession" with the 21-year-old.
Ayliffe-Chung had been in Queensland for six months before she was stabbed to death at a North Queensland backpackers in front of 30 witnesses on Tuesday night.
Queensland police arrested a 29-year-old French national, named by media reports as Smail Ayad, at the scene amid reports he shouted "Allahu Akbar" (God is great) during the attack and while being taken into custody.
A British backpacker, named in the media as Tom Jackson, 30, was critically injured after he tried to intervene and remains in hospital in a critical condition. A local man who also tried to help was stabbed in the leg.
"I can tell you the scene that confronted police was terrible ... there was a lot of blood, there were two persons, one was deceased and one was certainly in a very bad way," District Superintendent Ray Rohweder told the Townsville Bulletin.
The local newspaper also reports the alleged attacker told fellow backpackers he and Ayliffe-Chung were in love and married prior to Tuesday night's attack.
"Initial inquiries indicate that comments that may be construed of being of an extremist nature were made by the alleged offender," Deputy Commissioner Steve Gollschewski said in a statement.
"While this information will be factored into the investigation we are not ruling out any motivations at this early stage whether they be political or criminal."
Ayliffe-Chung had just qualified as a child care practitioner, and her travels had taken her to Morocco, Turkey, Thailand and India before she came to Australia on a one-year visa.
"The hardest thing living my dream, missing the important home things. Graduations, people in hospital, funerals and birthdays," she wrote in a July 20 Facebook post.
Deputy Commissioner Gollschewski said the alleged attacker appeared to have acted alone, is a visitor to Australia and has no known local connections.
"Police are not searching for anyone else in relation to the incident at this time. There is no known ongoing threat to the community arising from this incident," Deputy Commissioner Gollschewski said.
Tributes have poured in for Ayliffe-Chung from family and friends.
Former boyfriend Jamison Stead remembered her to the BBC as a "beautiful soul" who had "fallen in love with the country and its people".
"She was a beautiful girl who had her whole life ahead of her and we spoke of what the future may hold in store for her and what she wanted to do," he said.
Another friend, Kyle Godwin, described Ayliffe-Chung as "one of the happiest, full of energy, delightful, energetic and hilarious" people he had met.
"Today the world has lost one of the most beautiful young women to ever walk this planet. Today I lost a best friend," he said.