The California Office of Emergency Services (OES) was established as part of the Governor's Office in 1950 as the State Office of Civil Defense. In 1956, the agency became more involved in natural disaster operations, and the name was changed to the California Disaster Office. Adoption of the state's Emergency Services Act in 1970 changed the agency's name to the Office of Emergency Services. The Governor's Office of Emergency Services coordinates overall state agency response to major disasters in support of local government. The office is responsible for assuring the state's readiness to respond to and recover from natural, manmade, and war-caused emergencies, and for assisting local governments in their emergency preparedness, response and recovery efforts.

During major emergencies, OES may call upon all state agencies to help provide support. Due to their specialized capabilities and expertise, the California National Guard, Highway Patrol, Department of Forestry and Fire Protection, Conservation Corps, Department of Social Services, Department of Health Services and the Department of Transportation are the agencies most often asked to respond and assist in emergency response activities.

OES coordinates the statewide Fire, Law Enforcement, and Telecommunications Mutual Aid Systems based on the "neighbor helping neighbor" concept. As part of this Mutual Aid System, the state has been divided up into seven regions across California. Each region has an appointed coordinator that handles mutual aid request from the state and from within the individual region. Fresno County is located in Region V and the Region Coordinator is Sheriff Richard Pierce. During actual emergencies, OES activates the State Operations Center (SOC) in Sacramento and the Regional Emergency Operations Centers (REOCs) in impacted areas to receive and process local requests for assistance.

OES maintains the State Emergency Plan, which outlines the organizational structure for state management of the response to natural and manmade disasters. OES assists local governments and other state agencies in developing their own emergency preparedness and response plans, in accordance with the Standardized Emergency Management System and the State Emergency Plan, for earthquakes, floods, fires, hazardous material incidents, nuclear power plant emergencies, and dam breaks.

The OES Earthquake Program provides specialized earthquake preparedness planning and technical assistance to local governments, business, schools, hospitals, the public and other groups.