POLK CITY, Fla. – A deadly Polk County crash is under investigation. It happened shortly before midnight on Saturday at 18870 North Commonwealth Avenue. According to the Polk County Sheriff’s Office, a 34-year-old man from Orlando was driving a 2021 Mazda CX9 north on Commonwealth Avenue when he crossed the center line and slammed head-on into a 49-year-old Lakeland man who was driving a 2021 Toyota Corolla.