The suspect would have left the scene before police arrived, Travis Waas said at a news conference on Sunday.
According to Waas, multiple law enforcement agencies at the mall responded to calls from gunfire in one of the mall’s main corridors around 3:30 p.m. local time.
The department does not identify the victim at this time.
Law enforcement officers are in the process of completing their secondary quest at the mall to locate and guide the patrons hiding during the incident.
According to Waas, investigators have identified and questioned several witnesses.
Waas emphasized that anyone with information about the shooting or suspect should contact Grand Chute police.