Prime Minister Malcolm Turnbull says the Federal Government is seeking answers about the "inexplicable" shooting of Australian Justine Damond by a police officer in Minneapolis.

Officer Mohamed Noor shot Ms Damond, 40, more than once from the passenger seat of his police vehicle on Saturday night (local time) after she had phoned 911 to report a suspected assault near her home.

Speaking on Channel Nine's Today Show, Mr Turnbull said something "clearly went tragically wrong".

"How can a woman out in the street in her pyjamas seeking assistance from the police be shot like that?" he asked.

Justine Damond was fatally shot by US police on Saturday night. ( Linkedin: Justine Ruszczyk )

"It is a shocking killing, it is inexplicable.

"Yes, we are demanding answers on behalf of her family and our hearts go out to her family and all of her friends and loved ones."

Around 300 friends and family members gathered for a silent vigil to remember Ms Damond at Freshwater Beach in Sydney this morning.

Candles were lit and flowers were released into the ocean to "honour, love and respect" the life of an "extraordinarily kind, funny, smart and loving woman".

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 23 seconds 23 s Justine Damond's family and friends held a silent vigil for the 40-year-old. (Photo: Johanna Nicholson)

Ms Damond's fiance, businessman Don Damond, has called for justice for the vet and yoga teacher, who has lived in the US since 2015.

Her father John Ruszczyk said yesterday that there was an "ugly truth" about the incident.

Ms Damond called police just before midnight on Saturday after hearing a possible assault taking place in an alley behind her Minneapolis home.

She was in her pyjamas when she approached the police vehicle.

Mr Noor, the first Somali-American officer at Minneapolis' 5th Precinct, was in the passenger seat and fired multiple times across his partner at Ms Damond, Minneapolis TV station KSTP reported.

The medical examiner determined Ms Damond died from a gunshot wound to the abdomen and her death is being treated as a homicide.

Mr Noor and his partner are on paid administrative leave.

Minneapolis police officer Mohamed Noor ( Star Tribune: City of Minneapolis )

Mr Noor had just two years' experience on the force but already had two other complaints levelled at him.

Mr Noor was sued earlier this year after a May 25 incident in which he and other officers took a woman to the hospital on a mental health hold.

The lawsuit claims Mr Noor and the other officers violated the woman's rights when they entered her home without her permission and Mr Noor grabbed her wrist and upper arm.

ABC/wires