Cal. LAB § 3367

(a) For purposes of this division any person voluntarily rendering technical assistance to a public entity to prevent a fire, explosion, or other hazardous occurrence, at the request of a duly authorized fire or law enforcement officer of that public entity is deemed an employee of the public entity to whom the technical assistance was rendered, and is entitled to receive compensation benefits in accordance with the provisions of this division. Rendering technical assistance shall include the time that person is traveling to, or returning from, the location of the potentially hazardous condition for which he or she has been requested to volunteer his or her assistance.

(b) Nothing in this section shall be construed to provide workers’ compensation benefits to a person who is any of the following:

(1) A law enforcement officer who is regularly employed by a local or state law enforcement agency in an adjoining state and who is deputized to work under the supervision of a California peace officer pursuant to paragraph (4) of subdivision (a) of Section 832.6 of the Penal Code.

(2) A law enforcement officer who is regularly employed by the Oregon State Police, the Nevada Department of Motor Vehicles and Public Safety, or the Arizona Department of Public Safety and who is acting as a peace officer in this state pursuant to subdivision (a) of Section 830.32 of the Penal Code.