The suspect is believed to have left the scene before the police arrived, Grand Chute police public information officer Travis Waas said during a news conference on Sunday.
Several police agencies responded to the mall at about 3:30 pm local time to calls for shots fired inside one of the mall’s main corridors, according to Waas.
The department is not currently identifying the victim.
Law enforcement officials are completing their secondary mall search to locate and track customers who took shelter during the incident.
Investigators have identified and are interviewing several witnesses, according to Waas.
Waas emphasized that anyone with information about the shooting or suspicion should contact the Grand Chute Police Department.