A police department is the law enforcement branch of local government that provides a community with security and crime control. State and local police departments hire, train and manage police officers who are responsible for responding to reports of crime and public safety concerns. A police department is usually organized with a police chief as the leading official, and includes police officers and detectives. In order to perform their jobs safely and effectively, the members of a police department are required to complete initial and ongoing training, including firearms safety, conflict management, and sometimes emergency health care and first response training as well. Although most of the staff at police stations, substations and precincts are police officers and detectives, police departments also include auxiliary police staff such as constables, who can be either part-time police officers or civilian volunteers.
All city police departments have an official headquarters building where they provide information about public safety, write police reports and complete administrative tasks. The nature of police work requires constant patrolling of the community, so most police officers are distributed in strategic locations around the community, and may patrol in vehicles. A police dispatch and emergency response office is important, since those staff receive inbound 911 calls and must timely dispatch officers to the scene of crimes and accidents. Each local police department is managed by a chief of police, while state police department managers are usually called police commissioners.
In general, there are three types of police departments or law enforcement agencies, classified by geographical jurisdiction. These are federal law enforcement agencies, state police departments, and local police departments. To some extent, local police departments also include county sheriff offices. Law enforcement agencies at the federal level include the the U.S. Secret Service, Federal Bureau of Investigation (FBI), Drug Enforcement Administration (DEA) and other specialized crime-fighting units.