Three males, Joshua Dillon, 18, and James Rivera, 20 and a 17-year-old, have been charged with murder.
A friend named Abdul said he was “torn apart” after learning of Mr Mahmoud’s death.
“Just heartbreaking to see him go so quick, still young,” he said.
“Adam was just a normal, outgoing person studying hard – he had a life ahead of him.
“This is just random, out of the blue,” he said.
He said when he learned of his friend’s death, he thought it was a dream.
“I thought it was all a dream to be honest, just a massive dream, just thought it was a big dream,” he said.
He described the 18-year-old as outgoing, down to earth, friendly and a person who made “everybody happy”
“[He was] a very, very genuine bloke, a very, very nice man.”
Another friend Ammer Osman was at Bankstown Local Court on Tuesday to see the three men who had been charged with the murder of Mr Mahmoud.
“It’s tragic cause, it’s devastating to die in such a way,” Mr Osman said.
He said Mr Mahmoud was a person who loved the outdoors, playing football and going jet skiing.
“He’s a very good kid – he had a bright future ahead of him, he’s just gone too soon,” he said.
The friends say they have no idea how Mr Mahmoud ended up in a fight that got him killed.
Detectives arrested Mr Dillon, Mr Rivera and a 17-year-old about an hour after the fight and charged them each with one count of murder.
Mr Rivera and Mr Dillon did not apply for bail and it was formally refused by Magistrate Elaine Truscott at Bankstown Local Court on Tuesday.
Mr Dillon’s lawyer Louis Angelovski said his client would be defending the charges against him.
Homicide squad detectives and officers from the Bankstown Local Area Command set up a large crime scene at three different locations across Panania on Monday night.
One of those locations was outside the convenience store, not far from Panania train station.
Forensic officers on Tuesday morning were also continuing to examine a nearby home, including the driveway and a ute parked out the front.
Police have appealed for anyone with information about the man’s death to contact Crime Stoppers on 1800 333 000.