'Loud sound' preceded US police shooting Australian woman

Police in Minnesota were startled by a loud sound prior to fatally shooting an unarmed Australian woman who had called them to report a possible assault, US investigators revealed Tuesday.

The state agency probing the killing of Justine Damond, also known by her maiden name Justine Ruszczyk, interviewed one of the two officers who responded to her emergency call on Saturday night in Minneapolis.

It was the first time since the incident that authorities offered more information about the circumstances, as community leaders and Damond's family complained they had few details over a killing that reverberated in her native Australia.

Damond had called Minneapolis police Saturday around 11:30 pm to report a possible assault occurring near her home. Two officers responded with their police car's emergency lights off.

Officer Matthew Harrity told investigators Tuesday that he had been "startled by a loud sound" near the squad car just before Damond approached, the Minnesota Bureau of Criminal Apprehension (BCA) said in a statement.

His partner, Officer Mohamed Noor, was in the passenger seat.

"Harrity indicated that Officer Noor discharged his weapon, striking Ruszczyk through the open driver's side window," the agency said.

The BCA did not identify the startling sound, but an unidentified officer recorded on a police radio conversation published by the website Minnesota PoliceClips, speculated it may have been fireworks that sounded like gun shots.

After the shooting, the officers provided medical aid until paramedics arrived, but Damond died at the scene of a gunshot wound to the abdomen, authorities said.

The officers' body-worn cameras were not on during the incident, and investigators appealed for witnesses to come forward.