A teenage boy is fighting for life in Sydney after being knocked out at a party overnight.
Emergency services found the 16-year-old boy unconscious with head injuries at a home in Gladesville just before 11.30pm Saturday.
Police were told the fight broke out among a group of young men and the teen was punched, causing him to hit his head on the ground.
Gatecrashers turned up to the party before the brawl erupted and spilled out onto the street, Macquarie Radio reports.
The victim was rushed to Royal North Shore Hospital in a critical condition. He is said to be undergoing surgery on Sunday.
Those involved involved in the brawl fled the scene before officers arrived, police said.
Detectives have established a crime scene and want anyone with information to come forward.