A Seattle Police officer shot and killed an off-leash dog after it attacked a female dog walker in the 7900 block of Renton Ave S early this evening. Seattle Police Department Force Investigation Team (FIT) detectives are on scene and investigating.A 40 year-old-woman was walking her leashed dog when a second dog ran up and attacked her and her dog, biting and seriously injuring them both. The female owner of the off-leash dog chased after it and tried unsuccessfully to corral it, and was bit and injured in the process.Two officers arrived within moments and one officer shot and killed the attacking dog. Neither officer was injured in the process.Seattle Fire Department Medics responded to the scene and transported the 40-year old woman to Harborview Medical Center (HMC), where she will receive treatment for serious bite injuries. The off-leash dog owner was transported to HMC as well, for treatment of minor bite injuries.The injured dog was transported to an animal hospital for treatment.Seattle Animal Shelter personnel have been notified and will be participating in the investigation.