Wauwatosa Police Chief Barry Weber said the shooting happened during a dispute on Friday afternoon between two groups. He said four “innocent bystanders” suffered what were believed to be non-life threatening injuries.
Investigators said the suspect ran out of the mall alongside other other people.
“We do know there was some sort of altercation, and that’s when the bullets started flying,” Mr Weber said during a press conference.
The name of the suspect has not been released, and authorities did not announce any charges. Investigators say they have recovered a firearm.
The mall was closed on Saturday, and investigators were on scene overnight. Shoppers were allowed back on Sunday, police said.