The 28-year-old man was shot four times in the stomach at Rhodes, in Sydney's west, just before 5am (AEDT) on Wednesday.

He was shot in the carpark at the corner of Walker and Gauthorpe Streets, police say.

The man, of Middle Eastern appearance, screamed out for help and stumbled 200 metres into Rider Boulevard before collapsing.

He is now in hospital in a critical condition and undergoing surgery.

Detective Superintendent Mark Jones said the victim was known to police.

"It's not simply a random shooting at this stage," he told reporters at the crime scene.

"He does certainly have a link to OMCG."

Residents from nearby unit blocks looked astonished as they made their way past the large sections of streets marked off by police tape to access public transport.

Detectives have placed 44 yellow markers where the man dripped blood as he stumbled through the streets.

The wounded man to came to rest in front of a large construction site in Rider Boulevarde, within 50 metres of a child care centre and Rhodes Waterside shopping centre.

"There was a man on the ground and (he was) screaming," a construction worker at the building site, who asked not be named, told AAP.

"Blood was pouring out and he was screaming.

"The cops told me it was a bikie shooting."

The man said the victim was of Middle Eastern appearance and said he understood at least one OMCG member lived in the unit block next to where the shooting occurred.

"I heard this bikie leader lived over there in the penthouse," the construction worker said.

He saw another man come out into the street and apply pressure to the victim's wounds before paramedics and police arrived at the scene.

Ashlea Nicholson was awake in her unit adjacent to the carpark where the shooting took place when she heard the gunshots.

"I heard a guy calling out for help," Ms Nicholson told reporters.

"Just 'help', over and over. At least 10 times.

"I wasn't sure if it was the actual guy because he sounded quite loud and strong, but it turns out that it was."

A pair of work boots and a bloodied shirt still lie on Rider Boulevard where the man collapsed.

As residents were leaving the area for work, hundreds were arriving in Rhodes to start their work day at the local business complex.

Wednesday's shooting follows the weekend shooting death of Faalau Pisu, 23, after he attended a wedding with alleged Comanchero bikies in Canley Vale in Sydney's southwest.

Senior officers from the State Crime Command, and possibly the gang squad, are expected to hold a media conference later on Wednesday.

A Comanchero member at the scene did not witness the shooting, but said bikie members congregated in all parts of Sydney.

"I've been a member of the Comancheros for 31 years," the man told AAP.

"Bikies hang out everywhere."

He also said that when he joined the Comanchero, members were motorcycle enthusiasts, but not any more.

"They're not bikies, they're gangs," he said.

He also labelled the fatal shooting of Comanchero member Faalau Pisu at a wedding on the weekend as "disgusting".