ST. LOUIS COUNTY, Mo. – A woman was seriously injured when she was struck by a car early Friday morning on Interstate 270. According to a crash report from the Missouri State Highway Patrol, the woman was struck just before 3 a.m. while she was walking on northbound I-270 near the Interstate 70 westbound ramp. The crash report said an unknown vehicle struck the 25-year-old woman and fled the scene.