Four people have been taken to hospital and police are speaking with a number of others following a brawl outside a liquor store in Otara.
Police say the fight on Franich Street began about 5.30pm on Tuesday when a boy was followed into the shop by other youths.
It then spilled onto the road and a female shop worker was struck in the head by a fence paling.
Witnesses who went to her aid became involved and were also hurt.
Police say the most serious injury was suffered by the woman's co-worker, who was stabbed in the leg.
Inspector Ian Brooker says officers are visiting several known addresses in an attempt to locate those responsible, but it is not believed that robbery was a motive.