By Carma Hassan, Holly Yan and Emanuella Grinberg

CNN

(CNN) -- A woman shot and killed by Minneapolis police had called 911 to report a possible crime near her home, a source who knew her said

Justine Ruszczyk called 911 on Saturday night because she thought a sexual assault might be taking place in a back alley near her home, the source said.

But after Minneapolis police arrived, an officer shot and killed Ruszczyk.

Police still haven't explain how, or why.

'Working to learn more'

The shooting happened as two Minneapolis police officers responded to a 911 call reporting a possible assault shortly before 11 p.m., Minneapolis Mayor Betsy Hodges said.

The officers were wearing body cameras, but they were not turned on during the incident, the mayor said.

The Minnesota Department of Public Safety is now handling the case. The DPS' Bureau of Criminal Apprehension said authorities are in the initial stages of investigation and are "working to learn more about the events that transpired."

"As mayor of our city, a wife, and a grandmother, I am heartsick and deeply disturbed by what occurred last night," Hodges said Sunday.

"There are still many questions about what took place, and while the investigation is still in its early stages, I am asking the BCA to release as much information, as quickly as they are able to."

The Hennepin County Medical Examiner's Office has not released the woman's autopsy report.

Shock in Australia

Ruszczyk was originally from Australia, though she was a US citizen because her father holds US citizenship, the source who knew her said.

Her death made headlines across Australia. The country's Department of Foreign Affairs and Trade said it is providing consular assistance to the woman's family.

Ruszczyk had lived in the United States since April 2014, and was living with her fiancé at the time of her death, the source said. They were planning to marry in August.

'She was a healer'

According to her website, Ruszczyk trained as a veterinarian and later became a yoga instructor and life coach.

On Sunday, members of Women's March Minnesota honored her in a vigil. Chalk drawings on the driveway where they gathered said she would be remembered as "a loving woman, a light to everyone."

"This woman was a beautiful light. She was a healer, she was loved. She should still be here," one woman said to applause.

"This should not have happened ... that could've been me, that could've been you, that could've been you, that could've been any of us," she added. "And we're gonna talk and we're gonna work as a community to make sure this doesn't happen again."

CNN's Stella Ko contributed to this report.