Mejid Hamzy was shot multiple times in Simmat Avenue in Condell Park on Monday morning.

The two killers had been stationed outside the 44-year-old victim's home, waiting for him to leave, police say.

He got up after the shooting and struggled about 100 metres to "an associate's house" before collapsing and dying.

Assistant Commissioner Peter Thurtell on Tuesday said the threat of retaliation from other gangland criminals was "very real".

"Obviously these are organised criminal syndicates who are targeting each other and they know who they are targeting and we want to make sure that it stays low," he said.

Detective Chief Superintendent Darren Bennett said there had been some progress in the investigation but would not name any suspects.

"There's clearly an element of planning in this," he told reporters.

"The victim is well known to the police and his activities in recent times will be certainly subject of our inquiries."

He confirmed his older brother, the Brothers 4 Life gang leader, had been informed of the murder.

Bassam Hamzy is serving multiple jail sentences after first being jailed for more than 20 years for murder.

He was later sentenced to at least another 12 years after he was found running a drug ring and ordering kidnappings from his prison cell using a contraband mobile phone.

The shooters fled in a car which was later found burnt out in nearby Yagoona and no weapon was found at the scene.

Australian Associated Press