A 42-year-old Warm Springs woman died after she was struck by a semi-truck and trailer and then another vehicle while walking Tuesday night on Highway 97 near Shaniko.  According to the Oregon State Police, a preliminary investigation indicated a fully loaded, blue Peterbilt semi-truck with trailer, operated by a 60-year-old Spokane man, was traveling southbound on Highway 97 near Bake Oven Road when it struck a pedestrian walking in the travel lane.  The pedestrian, Lutah Avis Wallulatum, was subsequently struck by a second unknown vehicle in the northbound travel lane.  The OSP believes she was walking along the highway after the vehicle she was traveling in broke down a short distance from the crash location.  Wallulatum was pronounced deceased at the scene.  Investigators are seeking witnesses or anyone who may have been traveling in the area at the time, especially people who were on Highway 97 between Shaniko and the Cow Creek Rest Area on Tuesday night between 10 p.m. and 11:30 p.m., and who may have seen pedestrians or reported possibly striking an animal in the area during that time.  Anyone with information is asked to call Oregon State Police dispatch at 800-442-2068 or *OSP (*677) from a mobile phone.