Officers were called in from as far away as the Perth CBD to move on troublemakers.
One person has been hospitalised after a number of uninvited guests wrecked havoc at a party in Waikiki overnight.
Police received several calls about the event on Mends Way where they found guests spilling out onto the street and smashing bottles.
One of the gatecrashers hurled a brick through a window on the street and narrowly missed a young baby.
A man was then assaulted and knocked unconscious when he tried to confront the brick thrower.
He was taken to Rockingham Hospital for treatment but has since been transferred to Fiona Stanley Hospital where he remains in a stable condition.
Investigations into the assault and reported property damage on Mends Way continue.
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