A 15-year-old Milwaukee boy who allegedly opened fire at a suburban Wisconsin shopping mall on Friday, sending eight people to the hospital, has been arrested, police said Sunday.

Wauwatosa Police Chief Barry Weber said the suspect was arrested Saturday night, adding that the shooting was the result of an altercation between two groups of people at Mayfair Mall.

“We do know there was some sort of altercation, and that’s when the bullets started flying,” Weber said during a Sunday press conference. 

While police on Friday said witnesses described the shooter as a white man in his 20s or 30s,