Convicted killer Michael Ibrahim is being treated in hospital after being shot in the shoulder in an attack in Sydney's CBD.

Mr Ibrahim is the younger brother of Kings Cross nightclub identity John Ibrahim.

Officers found Mr Ibrahim standing on the footpath in Macquarie Street, where he is understood to live, at about 10:30pm on Sunday.

Police said several shots were fired but only one bullet hit Mr Ibrahim.

The 36-year-old was taken to the nearby Sydney Hospital where he is being treated for non–life-threatening injuries.

Police said he was in a satisfactory condition.

A crime scene was established as officers searched the area between Bridge and Bent streets for evidence.

Mr Ibrahim was released from jail in August last year after serving more than seven years of a nine-year term for the 2006 fatal stabbing of Robin Nassour at Chiswick in Sydney's inner west.

As part of his bail conditions, Mr Ibrahim is not allowed to visit the Kings Cross area.

In 2012, while he was still in prison, Mr Ibrahim and an associate were acquitted of conspiracy to murder charges.

Police search for evidence along Sydney's Macquarie Street after Michael Ibrahim was shot. ( ABC News )

Detective Superintendent Allan Sicard said police were looking for potentially two gunmen, who were seen in a white car.

"Police believe there was a white car — a late model car, possibly an Audi — in the vicinity," he said.

"So if anyone saw anything suspicious in that location around a car like that, contact us on 1800 333 000."

Detective Superintendent Sicard said police did not yet know a motive for the attack.

"It's of great concern, that people choose to use guns in a public street," he said.

"That's something that we've worked very hard as New South Wales Police to eliminate or reduce.

"At this stage we have spoken to the victim; the victim is speaking to police."

Police have also interviewed witnesses and are obtaining any CCTV footage that may have captured the shooting.