Teenager Adam Abu-Mahmoud was comforted by his father and brother as he lay dying on a Sydney street with a knife in his back, a court has been told.

Three men, aged 17, 18 and 20 have been charged with murder, following the violent altercation in Sydney's south-west on Monday evening.

Police allege that about 5:30pm, Adam Abu-Mahmoud, who was 18, and several other males got into a fight with the three accused near a corner store in Panania.

In documents tendered to Bankstown Local Court, police allege Adam Abu-Mahmoud and his brother, Abdul, later found two of the men in a ute in nearby Anderson Avenue.

"Abdul Abu-Mahmoud walked over to the drivers' side window and punched it with his left fist, causing it to shatter," the police facts said.

Police allege one of the accused, 20-year-old James Rivera, got out of the ute holding a 10-centimetre knife.

Rivera did not apply for bail and it was formally refused.

"He has a knife, he has a knife," Abdul Abu-Mahmoud allegedly said.

Police claim the other male in the ute, a 17-year-old who cannot be named for legal reasons, got out of the vehicle and pushed Abdul Abu-Mahmoud over.

They allege 18-year-old Joshua Dillon, who was involved in the earlier fight, then emerged from a home in Anderson Avenue.

"At which time Adam Abu-Mahmoud was stabbed multiple times to his back, causing multiple wounds, with one strike leaving the knife in the back of the deceased," police said.

"I got stabbed ... I can't breathe," the victim told his brother, according to the police facts.

"You're going to be alright," Abdul replied.

Forensic police examining the scene of a stabbing on Anderson Avenue at Panania. ( ABC News: Siobhan Fogarty )

No evidence teen was armed: defence

Police said Abdul Abu-Mahmoud put his injured brother into a car and drove him away from the scene, while also calling an ambulance.

The victim's father, Mohamed, attempted to comfort his son while paramedics arrived.

He was taken to Liverpool Hospital for emergency surgery, but was pronounced dead around 7:00pm.

Michael Ainsworth, the barrister for Dillon told Bankstown court the prosecution case against his client was weak.

Mr Ainsworth said his client was inside his home and only went outside when he heard the ute's window smashing.

"There is no evidence that he was armed at any time," Mr Ainsworth said.

He argued the prosecution's case was weak and asked the court to consider his client's personal situation.

"He has a partner and an 18-month-old baby," he said.

However, Magistrate Elaine Truscott refused bail, saying the available evidence could not exclude Dillon from being potentially involved in the stabbing.

The trio will all appear at courts at later dates.