The Force functions as a unit of the National Park Service with jurisdiction in all Federal parks. U.S. Park Police officers are located in the Washington, DC, New York City, and San Francisco metropolitan areas, and investigate and detain persons suspected of committing offenses against the United States. Officers also carry out services for many notable events conducted in the national parks. The U.S. Park Police are able to effect an arrest without a warrant in any unit of the National Park System, the District of Columbia, and the environs of the District of Columbia.