The victim had been stabbed numerous times before arriving at Fairfield Police Station about 11pm on July 22.
He was treated by officers and paramedics then taken to Liverpool Hospital for treatment, and has since been released.
NSW Police went to a local fast food restaurant where they arrested three boys and a man in a parked car, and declared a crime scene at the car park.
A 16-year-old, two 17-year-olds and a 21-year-old were taken to the station for questioning.
The following day, one of the 17-year-olds was charged with wounding a person with intent to cause grievous bodily harm, affray and breach of bail.
He remains before the courts.
On Tuesday, local police and members of the riot squad carried out a search warrant at a Fairfield Home, where they seized a jacket and kitchen knife.
The items will be forensically examined, police said.
An 18-year-old man was arrested and charged with intent to cause grievous bodily harm, affray and breach of bail.
He was refused bail and appeared at Fairfield Local Court on Tuesday.
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