Wauwatosa Police Chief Barry Weber said in a news conference that the teenager was arrested Saturday night with a gun allegedly used in the shooting. Weber did not identify the teen nor say what charges he may face.
Several other people were arrested in connection with the shooting, said Abby Pavlik, a spokeswoman for the police department, but she did not provide details.
Authorities said the shooting followed an altercation between two groups at the Mayfair Mall in Wauwatosa, outside Milwaukee, on Friday afternoon. Among the wounded was a teenager.
Pavlik could not say whether the injured teenager was the suspected shooter, adding that several people in the two groups were wounded. Four bystanders were also injured, Weber said.
He said the shooter fled the mall as tactical teams cleared the space of patrons and worked to contain its 1.2 million square feet, a process that took several hours.
Pavlik did not say where the suspect was arrested.