The Emergency Service Unit (ESU) is part of the Special Operations Bureau of the New York City Police Department.

On July 7, 1925, former Police Commissioner Richard E. Enright established the Emergency Automobile Squad, which was the forerunner to today's ESU.

On April 10, 1930, Police Commissioner Grover A. Whalen issued General Order #20 [9] which created the Emergency Service Division and also placed it under the command of Inspector Daniel E. Kerr.

[10] They patrol as either U-5 (Brooklyn, Queens and Staten Island) or U-4 (Manhattan and the Bronx) and respond to major incidents within their assigned boroughs for the tour.

The team can be called upon to support any unit within the NYPD, federal law enforcement agencies or outside police departments upon official request for tactical entries.

The ESU canines are an integral part of the US-TF1 Urban Search and Rescue (USAR) Team as deployed by the Federal Emergency Management Agency (FEMA).

The Hazmat/Weapons of Mass Destruction Team is tasked with investigating and responding to any chemical, biological, radiological, nuclear and explosive (CBRNE) incidents and also assisting the Bomb Squad on suspicious package calls.

Officers assigned to the medical squad possess a minimum of a New York State EMT-Basic certification and should have prior experience working as an EMT.

Before being assigned to the medical squad, officers must pass a series of interviews along with a physical agility test demonstrating their ability to carry patients and equipment.