A GPS tracker has been found fitted to the car of a man who was ambushed and shot dead on a busy Sydney road before daybreak.

Jack Cheung, 35, was fatally shot in his driveway on North Rocks Rd at Carlingford around 5.30am on Wednesday, but his body was only discovered when plumbers arrived to work on the home 90 minutes later.

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7NEWS can reveal detectives have found a GPS tracker fitted to Cheung’s car.

Cheung lived at the property with his mother, who’s rushing home from a holiday in Thailand. She has been speaking with detectives across the day.

CCTV shows Cheung’s assassin arrived by SUV at 5.31am and was only in the area for three minutes. But homicide detectives are still probing when exactly the 35-year-old was critically injured.

Police are still hunting for the shooter and their car.

Jack Cheung was allegedly shot in his driveway. Credit: 7NEWS

7NEWS understands Cheung’s brother is a member of Sydney’s notorious Coconut Cartel, which exploded onto the city’s gangland scene earlier this year.

Detectives are probing links to the gangland wars.

“It’s not something that we’re discounting - but it’s not something that we can confirm at this time,” NSW Police Acting Superintendent Michael Marinello told reporters on Wednesday.

Police confirmed on Wednesday Cheung was known to them. He had been in court last month after he was found with an unlicenced gun.

A member of the public discovered the shooting victim’s body at 7am, police said. Credit: 7NEWS

Cheung was known in the neighbourhood for loving cars, even racing at Eastern Creek. His Hyundai was his life and is now pivotal to his death.

“We saw Jack all the time - he was very polite - he wasn’t rude in any way,” neighbours Isabella and Jeanette said.

“All he did was work on his car.”

Neighbours have been left in shock after the early morning brazen attack.

“Honestly, I’ve no idea. We are all in shock. Maybe he could be hanging around the wrong crowd,” Isabella and Jeanette said.

Neighbours heard gunshots before body found

Neighbours told 7NEWS they heard a gunshot roughly two hours before the grim discovery was made.

Marinello said investigations so far indicate multiple shots were fired.

“It does seem to be a very brazen attack,” Marinello said.

“We do not believe that this is a random attack, we believe this is an isolated incident and so we can reassure the public that there is no ongoing threat.

“There are people who were home at the time, and they are assisting us with our enquiries.”

Police will be speaking with witnesses, and collecting CCTV footage as preliminary investigations continue.

Detectives are now investigating whether the man was killed hours earlier, with neighbours hearing what sounded like a gunshot about 5am. Credit: 7NEWS