AN Australian woman has been shot dead by police in Minneapolis.
Justine Damond, 40, was fatally shot in an "officer-involved shooting" in the city's Fulton neighbourhood according to police.
The Sydney woman had been living with her fiance and son in Minneapolis.
Minneapolis police confirmed the incident in a statement.
"Two Minneapolis police officers responded to a 911 call of a possible assault just north of the 5100 block of Washburn Avenue South just before 11.30pm Saturday," it read.
"At one point an officer fired their weapon, fatally striking a woman.
The officer who shot the woman was under investigation by the Minnesota Bureau of Criminal Apprehension, which was interviewing witnesses and "incident participants".
Minnesota police wear body cameras, but the officers involved did not have their cameras turned on at the time.
Police said a squad camera also failed to capture the incident, and investigators were seeking to determine if any video of the incident existed.
Two officers responded to a 911 call about a possible assault in the alley off of West 51st Street between Washburn and Xerxes avenues around 11.30pm, according to a statement released Sunday by the Minnesota Bureau of Criminal Apprehension.
"At one point one officer fired their weapon, fatally striking a woman," the BCA said.
"Investigators are attempting to determine whether any video of the incident exists."
Ms Damond, who also went by the name Justine Ruszczyk, was engaged to be married.
Her stepson told the Star Tribune she had heard a noise from an alleyway and called police who attended the scene.
"She was out on 51st Street and she was shot," the son, Zach Damond, said.
"Basically my mum's dead because a police officer shot her for reasons I don't know.
"I demand answers. If anybody can help, just call police and demand answers. I'm so done with all this violence."
Mr Damond said the woman, reportedly an Australian in her 40s, was "passionate" and his "best friend".
"Basically my mum was shot for reasons I don't know," Mr Damond said in a video posted on Facebook on Monday morning (AEST).
"I just know she heard a sound in the alley so then she called the police and the cops showed up and she was a very passionate woman, she probably thought something bad was happening and then next thing I know they take my best friend's life."
Minneapolis mayor Betsy Hodges said she intended to find out why the officers' body cameras were not turned on.
"As mayor of our city, a wife, and a grandmother, I am heartsick and deeply disturbed by what occurred last night," she posted on Facebook.
The woman was to be married to Mr Damond, 50, in August, according to Hannah, a close family friend, the Star Tribune reports.
Friends have begun to pay tribute to the speaker and meditation consultant.
She has been described as an "incredible woman" and a "brilliant, well-known, local healer".
"My heart aches for her fiance and mother in law who often accompanied Justine while she taught some profound meditation classes, sound healing classes, and her Sunday messages at Lake Harriet Spiritual Community," Angela Pederson wrote on Facebook
"I am happy to have known Justine and her untimely, tragic death is a reminder to live life fully, love deeply, and take risks to love as we are not promised tomorrow."
The Australian Department of Foreign Affairs and Trade confirmed to news.com.au it was "providing consular assistance to the family of an Australian woman who died in a shooting in Minneapolis".
Mr Damond was on a business trip and returned home Sunday afternoon after the tragedy occurred.
Activist Mel Reeves, who was at the scene told his Facebook followers that a vigil to support the family would be held at 6pm Sunday on 51st Street near where the shooting occurred.
Hannah said the woman worked as "a spiritual healer" and that "she was the most loving woman" who "kind of flowed through the house so lightly."
The Hennepin County Medical Examiner will conduct an autopsy and release details, including the victim's name and the cause and manner of her death.
Investigators are also trying to determine whether video of the incident exists, as officers' body cameras were turned off at the time and cameras in the police car did not capture the incident, according to a statement from the Department of Public Safety.