Porter Ranch residents Danielle Michaels (L) and Michelle Theriault (R) hold signs outside Los Angeles City Hall during a demonstration ahead of the testimony before the Los Angeles City Council on the ongoing natural gas leak in the Porter Ranch area of Los Angeles, California December 1, 2015. [Photo/Agencies]

LOS ANGELES - California Governor Edmund G. Brown Jr. Wednesday declared the gas leak in Porter Ranch a state of emergency.

The massive gas leak, which was discovered on Oct. 23, 2015, at a well used for gas storage in Aliso Canyon, has forced thousands of local residents to evacuate from the small town about 30 miles from Los Angeles.

In his statement, Brown asked state departments and related companies to take all necessary and viable actions to stop the leak, protect public health and safety, ensure accountability, strengthen oversight.

The statement also urged all state agencies to "utilize state personnel, equipment, and facilities to ensure a continuous and thorough state response to this incident."

Earlier this week, Brown toured the Aliso Canyon Natural Gas Storage Facility, including the site of the leak and one of the relief wells.

The Governor's Office of Emergency Services has established an incident command structure, including a physical post on-site at Aliso Canyon to better coordinate the local, state and federal response and information sharing, the governor's office said.

It is also maintaining a public webpage to provide real-time information regarding the state's multi-agency response and air quality monitoring, it said.

The Division of Oil, Gas and Geothermal Resources is investigating the leak and overseeing Southern California Gas Company's efforts to stop it, including issuing emergency orders in November and December directing Southern California Gas Company to halt gas injections into the storage facility, immediately work on alternatives to stop the leak and provide testing results, data, daily briefings and a written plan and schedule for sealing the well.

The Office of Environmental Health Hazard Assessment is reviewing air quality measurements, evaluating public health concerns from the gas leak and assisting other state agencies in determining whether additional actions are needed beyond those already required by local public health agencies.

The California Public Utilities Commission is investigating the gas leak to determine its cause and any possible violations and is collecting information about the costs of responding to and fixing the leak.

The California Air Resources Board is measuring the leak rate and estimating total methane emissions over the duration of the leak and is using ground-level monitoring, specially-equipped airplanes, and satellite information to provide updates of emissions.

Last month, Brown sent a letter to the CEO of Southern California Gas stating that the company's response has been "insufficient" and must be sped up, while noting that state agencies' multiple ongoing investigations will be coordinated with the California Attorney General's Office.