In the United States, mountain search and rescue is a technical specialty within general search and rescue. It is handled by 'career, on-duty and on-call paid' teams within the national parks, and supplemented by other paid and volunteer assets/resources as needed. For areas outside the national parks, there are approximately 20 agencies, mostly sheriff's departments, in the U.S. which provide paid or career members of a mountain SAR team. Most of those supplement with volunteer professionals. The bulk of mountain SAR operations in the U.S. are provided by 'volunteer professional' teams (are not career positions or paid but must meet minimum industry-accepted standards at or above their paid counterparts), who may also respond via mutual aid or automatic aid to incidents out-of-county, out-of-state and into national parks, via intrastate, interstate, and national park agreements, as well as via the FEMA NIMS national mutual aid deployment system.