Grand Chute Police named Dezman Ellis, 17, as the prime suspect in the shooting at the Fox River Mall on Jan. 31. Police believe that Ellis specifically targeted the victims.
When the shooting started, police warned shoppers to shelter in place while advising the public to avoid the area. Some shoppers immediately fled the scene.
Haylie Mirr, who works at a mall restaurant called Box Lunch, said she didn't know anything about the shooting, but said: "People just started running. We just locked the doors, and we had four customers in the store, we brought them to our back room."
Shoppers waited for three hours before police gave an all-clear.
Jovanni J. Frausto, 19, died at the scene, while a second person was taken to a hospital with non-life-threatening injures and later released.
Ellis allegedly fled the scene in a blue 2012 Dodge Avenger with a state license plate.
Officials announced that the mall will remain closed on Monday, though stores with outside entrances may continue to operate, the Post Crescent reported.
This was the second recent mall shooting in Wisconsin: eight people were injured in a shooting in November.
Police warned that Ellis should be considered armed and dangerous.
The Associated Press contributed to this report.