John Ibrahim's nephew, Hassan "Sam" Sayour, was today due to marry Aisha Mehajer, the sister of Salim, who is known for his legal battles and his own lavish wedding.

Emergency services were called to a home in Price Street, Merrylands at about 10.45pm and found Ngata with a single gunshot wound to the back.

The 59-year-old was taken to Westmead Hospital, where he remained on Saturday morning in a serious but stable condition.

A source close to one of the families has told Fairfax Media members of the Ibrahim family were at the house John's mother, Wahiba, on Friday night setting up for the wedding when Ngata was shot.

Police are investigating whether a burnt-out car found nearby in Mays Hill shortly after the shooting may be connected to it.

Chief Inspector Bradfield Peters of Holroyd Local Area Command said the gunman may have come through a side fence into the backyard of the home, where Ngata was socialising with several people.

Mr Peters said extra officers had been deployed to ward off possible reprisal attacks after the "brazen" shooting.

Ibrahim's mother lives in a flashy home on Price Street that her son rebuilt for her after she rejected a home he bought for her in Dover Heights.

Ngata has worked as a bodyguard for nightclub boss John Ibrahim for more than a decade after the pair met in Kings Cross in the 1990s.

He was once arrested in a raid on his home that netted bulk quantities of a methamphetamine precursor.

It's not clear if the shooting is related to the August arrest of two Ibrahim brothers, Michael and Fadi, who were caught in a dramatic sting in Dubai. Michael Ibrahim has been and charged over the attempted importation of 1.9 tonnes of MDMA, ice and cocaine. Fadi Ibrahim is accused of drawing $800,000 from the mortgage on his house to help fund his brother Michael's alleged international crime syndicate, and then being repaid $1.6 million.

Michael Ibrahim was allegedly two-timing between rival Sydney drug syndicates helmed by two warring Middle Eastern crime families.

During the massive police operation, John's house was raided but he was not alleged to be involved. Fadi has since been released on $2 million bail but Michael remains in custody. The only brother not in custody or facing charges at the moment is John.

All four Ibrahim brothers - John, Fadi, Sam and Michael - have been shot or stabbed over the course of their life.

The most recent was a drive-by shooting that hit the youngest, Michael, in the shoulder as he stood on Macquarie Street in the CBD one night in January 2015. He had been released from prison five months earlier after serving time for manslaughter.

Mr Sayour, the son of the Ibrahims' sister Maha Sayour, was shot himself in a dispute at Old Guildford in February 2011. The then 19-year-old was shot twice in the groin while two of his associates were also wounded.

In a lengthy interview in 2014, John Ibrahim told the Australian Financial Review he was unimpressed with criminals in Sydney.

"Who really shoots other people's houses in the middle of the night?" he said.

-with Patrick Begley

This story was amended to remove the assertion that Fadi Ibrahim has been charged over the alleged importation of 1.9 tonnes of drugs. Fadi Ibrahim is facing money laundering charges.