The Philadelphia Police Department (PPD or Philly PD) is the police agency responsible for law enforcement and investigations within the City of Philadelphia, Pennsylvania. The PPD is the countrys oldest municipal police agency, fourth largest police force and sixth largest non-federal law enforcement agency. Since records were first kept in 1828, at least 270 PPD officers have died in the line of duty. The PPD employs over 6,400 sworn officers and over 800 civilian personnel, and patrols an area of 369.4 km² (142.6 mi²) with a population of almost 1.5 million. The department is subdivided into 21 patrol districts, and like many other large municipal police forces, it incorporates many special units such as a K-9 squad, SWAT, bomb squad, community relations unit, and marine unit. The highest-ranking officer is Commissioner Richard Ross. The head of the PPD is the commissioner, who is appointed by the mayor. The current commissioner is Richard Ross (2016 – Present). Under the commissioner are two three-star deputy commissioners. The First Deputy Commissioner heads Field Operations. The Deputy Commissioner and Chief Administrative Officer heads Organizational Services, Strategy, and Innovation.