A 48-year-old man died after being shot at a Phillip unit just before midnight on Thursday.
Detective Inspector Marcus Boorman said emergency services received several calls about a gunshot in Mansfield Place about 11.45pm on Thursday night.
The man was found with a single gunshot wound.
Paramedics assessed the man at the scene then took him to hospital with life-threatening injuries.
The man later died in hospital.
Detective Inspector Boorman said police were unsure of the reason for the alleged attack but there was no evidence to suggest it was related to outlaw motorcycle gangs.
"A crime scene has been established. We have located a number of items that we will be forensically examining and we're following a number of avenues of inquiry," he said.
"At this stage the investigation is in its early stages, and we're calling for anyone that has any information in relation to this shooting to contact police and also anyone that would have any CCTV footage, dashcam footage in Mansfield Place area at the time to contact police."
Police confirmed this morning they had not found the gun used in the shooting, as investigations continued on scene.
Detective Inspector Boorman said a woman was also in the unit at the time of the incident. She was uninjured and called emergency services. The woman is being assisted by police.
"What I can say at this stage is police believe there was more than one offender involved. I can't say any more than that in relation to that," Detective Inspector Boorman said.
He did not say what type of firearm was used in the alleged attack.
He said police officers had been working at the scene throughout the night and would remain in Mansfield Place for some time as the investigation continues.
A man in a nearby unit said disturbances were frequent in the residential street, which has tightly-packed units and townhouses with shared driveways.
It is not the first time police have investigated a death in Mansfield Place.
On New Year's Day in 2014, grandfather Miodrag Gajic was bashed to death at his one-bedroom unit in the street.
Danny Klobucar was found not guilty of the murder in 2016 due to mental impairment.
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