An 18-year-old man has been killed and one man remains in custody after a brawl erupted at a party in Sydney's southwest.
Police say the fight broke out at a home in Ingleburn just before 9.40pm on Friday before it spilled onto the street.
The crowd grew bigger on Chester Road as more people arrived in vehicles, bringing with them a number of weapons including a baseball bat, golf club and wooden and metal poles.
"It was a chaotic scene," Detective Chief Inspector Michael Moroney told reporters on Saturday.
Emergency services discovered the teenager on the road with serious head injuries and he was pronounced dead at the scene.
The 18-year-old was reportedly attending a 16th birthday party.
"Obviously this is a very tragic set of circumstances, a young 18-year-old boy who goes out for the evening, and has been killed in such a brutal manner," he said.
Four men, all aged 19, were arrested at the scene and three were released without charge. One remains in custody at Campbelltown Police Station on Saturday night.
Det Insp Moroney said inquiries were continuing into why the fight broke out at the party, which was attended by 50 to 80 people.
Several crime scenes were established and police have appealed to anyone with information or footage to come forward.
