A 17-year-old was stabbed and critically injured after a 13-year-old girl's birthday party in Five Dock went out of control overnight.
The girl's grandmother, Christine Varricchio, said the birthday party was gatecrashed by older teenagers.
"She just tried to have a party with pizza, and all she bought was lemon squash and strawberry sarsaparilla," Ms Varricchio said.
The girl's mother was home and upstairs at the time, but could not hear what was happening because of loud music. The party was supposed to be low-key, with only a "handful" of invited guests, Ms Varricchio said.
A 16-year-old boy remains in police custody following a stabbing at the gatecrashed birthday party in Five Dock on Friday night.
Police were called to the home in Charles Street about 8.40pm after receiving reports of a fight. Two 17-year-old males were taken to Royal Prince Alfred Hospital with injuries.
One had stab wounds to his chest and side. He was in a critical but stable condition on Saturday morning. Police confirmed the other youth had been struck over the head by a bottle.
Ms Varricchio owns the property but did not witness the incident.
She arrived home to find police at the scene.
"I was waiting out the front of my place until 4am," she said.
It is not clear whether the victims were gatecrashers or invited guests. The 13-year-old and her mother are understood to be distraught and have left the home for the day.
Ms Varricchio, who has worked as a mentor in the juvenile justice system, said she understood how boredom and alcohol can trigger these events.
"I know these kids around here. They're all full of youthful exuberance and their needs just aren't being met, or satisfied," she said.
"I busk at Central station. I've seen them wander around with their alcohol bottles ... all looking for somewhere to go."
Ms Varricchio said two broken plastic chairs remained in the backyard, which she believes may have been used as weapons. Articles of clothing also remain, including a pair of stilettos.
No charges have been laid but Inspector Michael Penfold of Burwood Police said the 16-year-old is continuing to assist with inquiries. Police have spoken with several witnesses but are appealing for more information.
- Sydney Morning Herald