US cop who shot dead Aussie may have been spooked by fireworks

Authorities may investigate whether nearby fireworks startled a US police officer that shot dead an Australian bride-to-be.

Devastated friends and family of Justine Ruszczyk Damond remain in the dark as to why Minneapolis police officer Mohammed Noor shot her in the stomach after she called 911 to report an assault.

The 40-year-old Australian died from a gunshot to the abdomen after Noor allegedly fired at Ms Ruszczyk Damond across his partner Officer Matthew Harrity who was talking to her at the time.

Now a Minneapolis law enforcement source said it "would be good common sense to investigate" whether it was fireworks that spooked the junior officer.

Officer Mohamed Noor was allegedly sitting in the passenger seat of a police car when leaned over and shot across his partner. Source: Minneapolis Police Department

Justine Damond was shot dead by police outside her Minneapolis home. Source: AAP

The reference to fireworks is heard during the police radio conversations between Officer Noor, his partner Officer Matthew Harrity, the police dispatcher co-ordinating the emergency call and other officers rushing to scene.

At one point the dispatcher asks for a precinct sergeant to acknowledge a report of "two shots heard from the east".

"We heard those sounds from the station," an officer responds.

"Those are probably aerial fireworks."

Noor joined the department in March 2015. Source: Facebook

Officers Noor and Harrity, both new to the police force, had their body cameras switched off during the incident.

The possible link comes as Officer Harrity admitted he was "stunned" when his partner leaned removed his weapon and shot Ms Ruszczyk Damond

• The US cop 'who shot dead Australian woman in her pyjamas'

• Australian bride-to-be gunned down by junior cop 'for no reason'

• Heartbroken son speaks after Justine Ruszczyk Damond shot dead by police

• Why were police body cams switched off during fatal shooting of Australian woman?

Her heartbroken fiancé, Don Damond, spoke out on Monday criticising law enforcement for failing to offer details on why they killed the woman he was preparing to marry.

"Sadly, family has been provided no additional information from law enforcement regarding what happened after police arrived," Mr Damond said.

"It is difficult to fathom how to go forward without her."

She was engaged to marry her 50-year-old partner Don Damond in August.

Don Damond said he had been left in the dark as to why authorities shot and killed the woman he was supposed to marry. Source: Twitter

Back home, friends and family gathered on Sydney's Freshwater beach for a silent vigil to farewell the former Manly High student.

Led by her father John Ruszczyk, a large crowd gathered on the north shore beach for the sunrise on Wednesday.

Participants lit candles and placed pink flowers on the water in her memory.

On Wednesday morning Minneapolis Mayor Betsy Hodges said she too was desperately waiting on information from the police department.

"I don't know what the answers are," she told Good Morning America on Tuesday.

"That's the trade-off of an independent investigation.

"We aren't in charge of it.