An Australian woman has been shot dead by police in the US city of Minneapolis in an incident in which the officers did not have their body cameras turned on.
Police responded to reports of a possible assault in an alley behind a home about 11.30pm on Saturday, local time.
One police officer fired their weapon, killing 40-year-old Sydney woman Justine Damond.
Ms Damond, also known as Justine Ruszczyk, was a trained veterinarian who worked as a spiritual healer and meditation teacher.
Friends said she was engaged to be married to a Minneapolis man, Don Damond.
She called police after hearing a disturbance in the alley and went out to investigate when she was shot, according to media reports.
The Australian Department of Foreign Affairs and Trade said it was providing consular assistance to the family of an Australian woman who died in a shooting in Minneapolis.
The Minnesota Bureau of Criminal Apprehension (BCA) said in a statement on Sunday that police officers had responded to an emergency call about a possible assault in an alley behind a home in the Minneapolis suburb of Fulton.
"At one point, one officer fired their weapon, fatally striking a woman," the BCA said.
Investigators are trying to locate a video of the shooting, as officers' body cameras were turned off at the time and cameras in the squad car did not capture the incident, the BCA said.
"The officers' body cameras were not turned on at the time and the squad camera did not capture the incident," the BCA said in a statement.
"Investigators are attempting to determine whether any video of the incident exists."
Ms Damond ran her meditation workshops at the Lake Harriet Spiritual Community, which paid tribute to her in a Facebook post.
"We are so sad to report the tragic shooting of Justine Damond," the community's post said.
"Justine was one of the most loving people you would ever meet. We can't even imagine LHSC without her."
Ms Damond is believed to have been living in the US for at least the past three years.
Zach Damond, the son Don Damond, told The Star Tribune the woman "heard a noise in the alley and called the police".
The woman was to be married to Mr Damond, 50, in August, a family friend said.
The friend told The Star Tribune the woman worked as "a spiritual healer", remembering her as "the most loving woman".
"She and Don were just so in love," the friend said. "She lived such a full life."
Minneapolis Mayor Betsy Hodges told a news conference at City Hall late on Sunday: "I am heartsick and deeply disturbed by the fatal officer-involved shooting that happened last night.
"I know the neighborhood well," said Ms Hodges, who represented the area for eight years as a City Council member, The Star Tribunereported.
"We have few facts at this point," she said.
"I want to know more. I call on the BCA to share as much information with all of us as quickly as they can. I have questions about why the body cams weren't on," she said.
Regarding last night's shooting - I’m seeking answers and will make sure to keep the communication flowing: https://t.co/XkmKYBP4l8— Betsy Hodges (@MayorHodges) July 16, 2017
Almost 200 people gathered near the scene of the shooting for an evening vigil paying tribute to the dead woman.
Mr Damond was out of town on a work trip, returning to Minneapolis on Sunday afternoon, local time.
Authorities will conduct an autopsy and release details about the manner and cause of Ms Damond's death, the BCA said.
A man, claiming to be Zach, gave an interview to Women's March Minnesota on Sunday afternoon, saying the police were not being transparent about his mother's killing.
"My mom is dead because a police officer shot her for reasons I don't know, and I demand answers," he said.
"America sucks," he added.
Friends and neighbours of the dead woman left signs at the vigil asking why her life was taken.