The victim, 20-year-old Antonio Hermiz, was shot in the head and killed on Friday afternoon while children played nearby in the popular Lizard Log park in western Sydney.

His 18-year-old companion Ronaldo Odisho was shot in the chest and taken to Liverpool hospital where he remains in a stable condition.

Fairfield Police Superintendent Peter Lennon said police were investigating whether the targeted attack was linked to a drug dispute.

"These two that were shot are well known to police, well known to local police and well known to state crime command," he said.

"I think it's a gutless attack by these people, we've got people who at Christmas time are enjoying themselves with their family in a parkland and this sort of thing goes on."

A NSW Police spokeswoman said gang links were a "line of inquiry".

Speaking just outside the crime scene on Saturday morning, NSW Labor's police spokesman Guy Zangari called on the government to step in to protect residents in the area by resourcing extra officers.

"I am here today as a result of the escalating gangland violence in south-west Sydney," he said. "It's not just of the streets, it's in front of houses and in parks.

​"Locals are scared, a daylight murder has occurred in a park," he said.

"I feel for the families who had to witness this just before Christmas. Can you imagine children having to witness a murder in front of them? It's terrible."

Bossley Park resident Martin Warner, who walks his Labrador Bailey in the park every day said the area had become more dangerous over the past 6 months.

"There's been a few shootings in the area," he said. "It's getting worse and worse."

"It's Christmas Day tomorrow, so I wonder how [the victims] family feels. There are a lot of young families in the area, so I'd hate if there was a stray bullet."

Superintendent Lennon said the car believed to be carrying the shooters fled the scene in Wetherill Park.

On Friday police had no description of the car or the individuals involved.

A spokeswoman confirmed there had been no further developments identifying the perpetrators on Saturday morning.

An extensive crime scene has been established in the park, which is being examined by specialist forensic officers. Superintendent Lennon said Strike Force Jacoby had been formed to investigate the shootings.

With Rachel Olding, Jodie Stephens