A head-on car-semi crash killed a Shelby County youth last night on Highway 59 south of Denison. Authorities have identified the victim as 16-year-old Dena Carter of Irwin and say she was driving north when her car crossed the centerline and hit a semi driven by a 58-year-old Ocala, Florida man. Carter was thrown from her car, and was pronounced dead at the scene. The semi driver and a passenger were taken to the hospital in Denison, treated for head injuries and released.