A teenage boy is awaiting surgery in hospital after he was stabbed at an out-of-control house party in Sydney northwest.
Riot police and local officers were called to the party on Nelson Road at Box Hill around midnight after a fight broke out in which the teen suffered a stab wound to his stomach.
He was taken to Blacktown Hospital by his friends and is currently is a stable condition awaiting surgery.
Police attended the premises and found about 100 people at the party, which was quickly broken up.
A 17-year-old boy was arrested at the scene and is being interviewed by police.
Police have established a crime scene and inquiries are ongoing.