Former Comanchero bikie chief Mahmoud 'Mick' Hawi is on life support after being shot outside a gym in Rockdale, in Sydney's south.
Officers were called to the incident at the Fitness First gym on West Botany Street shortly after midday.
Mr Hawi was in his black luxury four-wheel drive when he was shot at least half a dozen times.
He went into cardiac arrest and was taken to nearby St George Hospital.
A car which was torched and then abandoned in Chandler Lane at Rockdale is understood to be the getaway vehicle.
NSW Police Media had earlier confirmed Mr Hawi had died, however he is understood to be on life support with a grave prognosis.
Witnesses tried to resuscitate Hawi
One witness, who said she heard about six gunshots, was in disbelief that there was a shooting in her suburb.
"I didn't think that they were gunshots … I mean Rockdale … I don't think that that happens here," she said.
"It was kind of chilling to think it happened across from where I work or where I sometimes park my car … I won't be doing that anymore."
Another witness said she saw people coming out of the gym after the shooting who appeared "really traumatised".
Rup Sarkar, who works at the physiotherapy clinic next to the gym, said Mr Hawi was a regular.
"Everyone knows him, he's a nice guy," he said.
Mr Sarkar said it was hard to look on as he came out of the gym to see people trying to resuscitate Mr Hawi.
"There was blood … I tried not to look."
"Not your average Thursday I guess."
Reshan Muthukrishna, who owns the physiotherapy clinic, said the gym was a hub for bikie gang members.
"There have been minor incidents with gangs and gang members coming to train here," he said.
"Previously there has been some instances in the car park.
"But life goes, people train, people come and go."
Mr Muthukrishna said this shooting would affect both the gym and physio clinic's clientele.
"It's definitely not good for business."
Crime chief kept low profile
Sources say Mr Hawi has kept a low profile in recent years after he served a prison sentence for manslaughter over the death of Hells Angel bikie Anthony Zervas in a brawl at Sydney Airport in 2009.
During the airport brawl Anthony Zervas was bashed with a metal bollard and stabbed several times.
Hawi was convicted of murder and sentenced to 28 years in prison after a nine-month trial in 2015, but the NSW Court Of Criminal Appeal overturned his conviction on a number of grounds.