Crime figure executed in Sydney's CBD

Multiple gunmen have opened fire on underworld figure Bilal Hamze in Sydney's CBD, killing the notorious gangster in what police say is a major escalation of gang violence in the city.

The 34-year-old was peppered with bullets as he left a restaurant on Thursday night in Bridge Street, near Circular Quay and died shortly after in St Vincent's Hospital.

He is the cousin of Brothers for Life figurehead and Goulburn Supermax inmate Bassam Hamzy.

Detectives believe it's part of an ongoing conflict between the rival Hamze and Alameddine families and organised crime networks or the result of arrests made last week under Operation Ironside - an international sting on organised crime.

NSW Police Homicide Squad Commander Detective Superintendent Danny Doherty said "once you disrupt organised crime networks, there is always going to be some irritation, and this may have been a result of that".

It was fortunate members of the public weren't injured during the "brutal execution-style murder", he told reporters on Friday.

"We're lucky that we haven't got more casualties. We are lucky that there is no one else injured.

"It is a major escalation ... There were still people leaving pubs, restaurants and other places and motels."

Police are poring over the area and also examining a burnt-out black Audi found at Northwood on Sydney's lower north shore that's been linked to the shooting.

Criminal Groups Squad Commander Detective Superintendent Robert Critchlow said there were concerns about revenge attacks.

"We'll be opening doors, we'll be kicking down doors, we'll be tipping people over," he said.

"It will not be business as usual for the criminal fraternity in Sydney after today."

Police confirmed there was a contract out on Hamze's life.

"He's been warned that he was at risk ... He sought to live his life the way he wanted to, and he made some choices," Det Supt Critchlow said.

Detectives are investigating how the assailants knew about Hamze's whereabouts.

Nearby resident Rachael, who didn't want to give her last name, told AAP the Sydney shooting had left her 'shaken'.

"I used to live in Los Angeles where gunshots were often heard but it's very unusual for shootings to happen here in Sydney, especially so close to where I live and work," she said.

The ongoing feud between Sydney's Hamze and Alameddine crime families stretches back years.

In 2013, Hamze's mother, Maha Hamze, was shot in the legs through the door of her western Sydney home but survived.

The shooting was sparked by a debt recovery fee feud between her son and another man.

Her home was shot up again last October and on the same day, Hamze's cousin Mejid Hamzy was shot dead at his Condell Park home.

Detectives from the NSW Police State Crime Command's Homicide Squad have established Strike Force Englorie to investigate the death.