Update 11.30am: An 18-year-old man has been seriously injured after being stabbed at a party in Wanneroo last night.
The victim and another guest were involved in an altercation about 10.15pm at the party on Frederick Street in Wanneroo.
The argument moved to the front yard of the property as other guests became involved.
The victim then received a stab wound to his chest and was rushed to Royal Perth Hospital where he was in a serious condition last night.
This morning, he remains in hospital in a stable condition.
The offender is believed to have fled in a vehicle.
He is described as dark-skinned, of slim build and around 15-16 years old. He had a shaved head.
Anyone with information is asked to call Crime Stoppers on 1800 333 000.