Specialist police units have descended on south-west Sydney as they investigate the shooting of underworld figure Mejid Hamzy and attempt to prevent an outbreak of violent reprisals.

Hamzy, the brother of notorious Brothers for Life founder Bassam, was killed outside his home in Condell Park on Monday morning, shot by a pair of gunmen in a seemingly planned ambush that has the NSW Police gangs squad investigating why the 44-year-old was targeted.

Senior NSW Police officers warned the possibility of retaliation was a significant concern and said they would be targeting the known associates of Hamzy to prevent them going after suspected killers.

"We will be targeting associates and known offenders," Assistant Commissioner Peter Thurtell, South West Metropolitan Region Commander, said.

"They can expect us to be in their face. They know we will be knocking on their door."

Assistant Commissioner Thurtell said the public order riot squad, south-west Sydney operational support group, dog unit, PolAir and other units were involved in the sweeping operation.

Hamzy has been linked to the 2016 death of Hamad Assaad, who was linked to the 2013 shooting of Hamzy's aunt, Maha Hamze, who survived.

Police are examining whether the Assaad killing is relevant to the death of Hamzy on Monday as well as any relationship with recent public shootings in south-west Sydney.

In a separate incident on Saturday, shots were fired on the Auburn street where Hamzy's aunt lives.

"The victim is well known to the police and his activities in recent times will be certainly subject to our inquiries," Detective Chief Superintendent Darren Bennett, State Crime Command Director, said.

Hamzy was shot multiple times in his driveway before running a short distance to an associate's house around the corner, where he died from his wounds. The shooters fled the scene in a car.

One resident on Hamzy's street told the Herald they heard around eight gun shots, which accords with other witness statements made to police.

The neighbour said their home security cameras had caught the assailants as they left the scene, wearing all black clothing and balaclavas as they fled to a getaway vehicle.

"The same outfit all of them [gangland shooters] wear," the person said.

The killing appears to have been planned and police are investigating whether the killers were hired to carry out the hit.

"That certainly could be the case," Chief Superintendent Bennett said.

"We are very concerned about the ongoing conflict between Middle Eastern organised crime groups in south-west Sydney."

Mejid's brother, Bassam, who has been informed of the killing, was convicted in 2001 for the murder of a teenager. He is in Goulburn Supermax serving a 21-year sentence. Bassam founded the Brothers for Life gang with his cousins in 2007 from his jail cell.

Mejid was involved in a number of businesses in the years before his death, including as the owner of Melt Chocolate Bar in Burwood.

He was recently charged with possession of illicit drugs and due to face court next month.

He was also charged in 2012 for his alleged involvement in importing methamphetamine but a jury could not reach a verdict during his trial and he was granted a permanent stay on his case.

Family friends outside his home on Monday said he was a "beautiful family man" and not that close to his older sibling.

At least the family friend didn't describe him as a "loveable larrikin", I guess.