Police are keeping a guard in place over the weekend at Whangarei Hospital, where three men are recovering from gunshot wounds.
Five people were injured in the gang-related incident at a Clark Road house in Kamo on Wednesday night.
The three men in Whangarei Hospital included the 21-year-old arrested in relation to the shooting, but he was yet to be charged.
Another man was discharged yesterday, and the fifth man was in Auckland Hospital, in a serious but stable condition.
Police said they have had a number of calls from the public and have not ruled out the possibility that others were involved in the incident.
Whangarei/Kaipara area commander Inspector Justin Rogers said police would continue to maintain a strong presence in the Kamo area and at Whangarei Hospital.