A second victim of a drive-by shooting outside a popular nightclub in Melbourne has died, as police look at the possible involvement of motorbike or crime groups in the attack, media report.
The nightclub patron - named in local reports as 28-year-old Richard Arow - died on Friday, police said.
Six people - five men and a woman - were injured in the shooting that occurred outside the Love Machine club in the trendy inner-city suburb of Prahran last Sunday morning, investigators said.
A 37-year-old security guard, named by local media as Aaron Khalid Osmani, died on the same day in hospital.
Police added in a statement on Saturday that they were continuing to investigate the incident.
Melbourne's The Age newspaper said police were looking into whether motorcycle or other crime groups were behind the killings, adding that patrons and staff had been threatened by gang members in recent months.
"Clearly tensions are escalating. We think this is a specific, targeted attack but we do not know the people involved in it or the motive at this point in time," Victoria Police Assistant Commissioner Tess Walsh told the newspaper.
"There are some commonalities with the crime type," she added, referring to the type of shootings carried out by bikie gangs.
A spate of shootings in Melbourne in March left five people dead in four separate incidents, two of which were believed to be gang-related.
Mass shootings are rare in Australia, which has strict firearms laws introduced in 1996 after 35 people were killed by a gunman in the historic colonial convict site of Port Arthur in the state of Tasmania.
Victorian Premier Daniel Andrews said following the Prahran shooting that his state government was ready to change gun laws if needed.