A YOUNG father was stabbed and savagely beaten to death with a baseball bat by a mob of up to 15 people who turned on him in Sydney's south-west yesterday.

Wayne Boyce, 23, from Bonnyrigg, was set upon in Trevanna St, Busby, just after 3am.

The father of two infant boys had driven to the address after a friend, known as Joel, called him for help when the angry group turned up at his house.

Neighbours said they awoke to the sound of smashed windows, as members of the group shouted for Joel to "come outside".

A car parked in the driveway was also badly damaged by the men, who had allegedly come after Joel for reasons which are still unclear.

It is understood he had called Mr Boyce, a long-time friend, who at first dismissed the problem, saying he should just tell the men to "go away". Eventually the dangerous situation became clear and Mr Boyce rushed over from his home in Bonnyrigg.

His brother-in-law, Mohammed, said the moment Mr Boyce arrived at the Busby address and got out of his car, the group turned its anger onto him.

He attempted to escape, but was stabbed in his lower back and fell to the floor where his killers continued to bash him with bats and metal poles.

Paramedics were called and attempted to revive him at the scene, but he died a short time later from his injuries at Liverpool Hospital.

Police yesterday formed Strike Force Harney to help track down his killers, who had fled the scene, and forensic officers and local detectives later secured evidence.

Authorities said the trouble had occurred as a result of an altercation between "two groups of men" outside the home.

Friends and family gathered at the home of Mr Boyce's parents, just metres away from where the attack occurred, to offer support.

His girlfriend, Casey Tyrell, 19, was too distraught to speak yesterday, but her mother described him as a beautiful soul who should not have died in such a senseless way.

"Wayne loved my daughter and my daughter loved him," Sharon Tyrell said.

"She loved him so much."

She said it was incomprehensible why he had to die.

"It was just a fight - they didn't have to bloody stab him," she said.