The police riot squad, at least one police helicopter and dog squad were called to a wild party involving about 150 young people at Gymea last night.
During a subsequent arrest at Gymea railway station, a police officer was injured when he was knocked to the ground and hit his head on concrete.
He was taken to St George Hospital, but later discharged.
Shortly before 8pm, police from Sutherland Local Area Command were called to a vacant house in View Street after complaints about a party.
They found about 150 people at the gathering.
While police were trying to identify the organisers, it is alleged a number of glass bottles and other projectiles were thrown at officers from the backyard of the property.
Additional police resources, including the Public Order and Riot Squad, Dog Unit and PolAir, were called in, after which the crowd began to disperse peacefully.
Speaking to 7 News Kyle Hood said he invited friends to the rental property after he and his mother moved out last week.
"I didn't mean for it to happen, I just like, standing there and I saw everything happening I couldn't stop it," he said.
He said his mother was also very upset.
‘’She’s very upset, she was talking to me just then, I’m going to see her for Mother’s Day,’’ he said.
Local police, assisted by the Police Transport Command, subsequently conducted patrols of Gymea railway station.
While on the platform, it’s alleged a male youth, 17, who had left the party, assaulted a man, 19.
The youth was arrested and taken to Sutherland police station, where he was charged with assault and resisting arrest.
He was refused bail and will appear before the children’s court today.
During his arrest, an officer was knocked to the ground, hitting his head on concrete.
The police officer sustained cuts and swelling to his head and was treated by paramedics, before being taken to St George Hospital.
He has since been discharged.
Sutherland police Acting Inspector Shane Jessep told 7 News that the scene was chaotic.
"Violently resisting arrest is of great concern, as is a gathering of a hundred, upward of a hundred young people drinking alcohol," he said.
Police are urging anyone with information to contact Crime Stoppers on 1800 333 000.