Medics were called to the scene on 1st Avenue South near S. Findlay Street just after 3 p.m., said Kyle Moore with the Seattle Fire Department.
The woman suffered severe injuries and medics were still performing CPR on her as they put her into the ambulance, Moore said. She was later pronounced dead at Harborview Medical Center.
Police say the woman was crossing 1st Avenue from west to east near the intersection when a 56-year-old man driving a truck west on Findlay Street came to the stop sign at 1st Avenue. He turned left onto 1st and collided with the woman, police said.
Officials say they are still investigating why the man didn't see the woman.