The King County Sheriff's Office (KCSO) is a local police agency in King County, Washington, United States. It is the primary law enforcement agency for all unincorporated areas of King County, as well as 12 cities and two transit agencies which contract their police services to the KCSO. KCSO also provides police and fire Aircraft Rescue and Fire Fighting to the King County International Airport (Boeing Field). KCSO also provides regional-level support services to other local law enforcement agencies such as air support and search and rescue. The department has over 1,000 employees and serves 2.1 million citizens, over 500,000 of whom live in either unincorporated areas or the 12 contract cities.