MOUNT VERNON, Wash. (AP) — A 16-year-old Mount Vernon boy has turned himself in to law enforcement for his involvement in the July 17 gang-related shooting at Walmart in Mount Vernon that left five injured. Police booked the boy into Skagit County Juvenile Detention. That’s according to a news release from the Mount Vernon Police Department. The boy will be held on a 30-day magistrate’s warrant to provide investigators time to reconstruct the events of the shooting through witness accounts, physical evidence, scene reconstruction, video footage, tips from the public. Three of those injured in the shooting were airlifted to Harborview Medical Center in Seattle. Two have been discharged from the hospital.