A teenager who survived being shot in the neck during an ambush in Sydney two weeks ago has been killed in another volley of bullets overnight just a kilometre away from where he was first targeted.

Bassil Hijazi, 18, was one of two men gunned down in Sydney's south within 15 minutes of each other on Monday night in the latest wave of gun violence to hit the city.

Homicide squad detectives are still investigating the shootings in the neighbouring suburbs of Bexley and Earlwood, but at this stage they do not believe the two deaths are linked.

The latest shooting occurred about 9.45pm on Monday when Mr Hijazi, a Comanchero associate, was shot multiple times in a car park on Albyn Street in Bexley.

Paramedics treated the teenager at the car park and took him to St George Hospital, where he was pronounced dead.

It was the second attempt on Mr Hijazi's life in two weeks.

On July 16, Mr Hijazi was shot in the neck as he sat in a car on Prince Street in Bexley.

Witnesses said two vehicles chased Mr Hijazi's sedan into the poorly lit street and cornered his vehicle, before someone emerged and fired up to six rounds into the car, one of which struck the victim in the neck. Mr Hijazi survived that shooting and staggered to a nearby home for help.

"It sounded like he emptied the whole magazine," one resident, who declined to be named, said at the time.

Just 15 minutes before Mr Hijazi was shot on Monday night, police were called to a separate shooting on Charleston Avenue in Earlwood. When they arrived they found a 35-year-old who had been shot multiple times.

Paramedics took the man to St George Hospital, where he underwent surgery but died early on Tuesday morning.

The two shootings occurred less than four kilometres apart, but the Homicide Commander, Detective Superintendent Mick Willing, said they were in no way linked, and both victims were known to police.

"People out there know who are responsible for the deaths of those persons overnight," he said.

"The persons responsible for these crimes do not care about the public, they are reckless. Someone out there knows who committed these crimes and we want them to come forward."

Police have set up crime scenes at both locations, and are investigating who is responsible.

Friends of Mr Hijazi are paying tribute to him on social media.

Ali Mawassi wrote on Facebook that Mr Hijazi was one of two people in the same family to have died in recent days.

"Two losses for the family in two days.. This pain is unbearable. Every time I close my eyes in an attempt to fall asleep I see my loved ones faces," he wrote.

Ali Najem wrote: "RIP. Bassil Hijazi - Going to miss ya to death brother love ya !"

Monday night's violence comes after a wave of shootings across the city in the past month, in which two other men were shot dead.

Hells Angels nominee Tyrone Lee Slemnik was shot dead outside an apartment block on George Street in Eastlakes. Ali Jammas, who also had motorcycle gang links, was shot dead outside a home in Abbotsbury.

Last week, Detective Superintendent Scott Cook, who is overseeing the strike force set up to investigate public shootings in Sydney, said a number of other recent, non-fatal shootings were drug related.

"The cause of these shootings appears to be at this stage low-level drug dealing between hoodlums who now have firearms and consider themselves to be gangsters," he said at the time.

"They're two-bit pretenders. They're not gangsters. They're just young hoodlums with firearms. It's very reckless what they're doing. It's out of control in terms of their behaviour."