An Australian woman has been killed by a US police officer responding to a 911 call in Minneapolis.
The Minnesota Department of Public Safety (BCA) said police responded to "a call of possible assault" when "at one point an officer fired their weapon, fatally striking a woman".
The BCA is investigating the Saturday incident but said the officers' body cameras were not turned on at the time.
The victim has been identified by Australian officials as Justine Damond.
According to Australian media, the 40-year old woman was living in Minneapolis with her fiancé. The woman called 911 to report a noise near her home when the incident occurred, reports said.
A man claiming to be Ms Damond's son also said in a Facebook video that she was the one who alerted authorities.
"She thought something bad was happening and the next thing I know, they take my best friend's life," the man, named Zach, said.
Minneapolis mayor Betsy Hodges said in a statement she was "heartsick and deeply disturbed by what occurred last night".
Over the past few years the US has seen a series of civilian killings at the hands of police that have caused widespread concern and criticism.
Ms Damond, nee Justine Ruszczyk, taught meditation classes at the Lake Harriet Spiritual Community.
She used the surname of the man she was expected to marry in August, Don Damond, according to the Minneapolis Star Tribune.
She is believed to have been living in the US for at least the last three years.
About 200 neighbours, family members and residents shocked by the shooting gathered for a vigil on Sunday night where she died.
"I mean ask anybody here, they're shocked," said Ms Damond's student Corey Birkholz told CBS News.
He described Ms Damond as "a very conscious, loving person and you wouldn't associate that with a gunshot in an alley".
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"I don't know anything about the law or police work to that extent but to me, it seems really stupid. You have a body camera, aren't you supposed to use them?" Mr Birkholz added.
Mayor Hodges echoed his sentiments, saying at a news conference: "I share the same questions other people have about why we don't have body camera footage of it, and I hope to get answers to that in the days coming."
The two officers involved in the shooting are on paid administrative leave.
The Australian Department of Foreign Affairs released a statement on Monday on behalf of Ms Damond's family.
"This is a very difficult time for our family," the statement said. "We are trying to come to terms with this tragedy and to understand why this has happened."