California Code, Government Code - GOV § 50086

No person who is summoned by a county sheriff, city police department, fire department, park ranger, or other local agency to voluntarily assist in a search or rescue operation, who possesses first aid training equivalent to the Red Cross advanced first aid and emergency care training standards, and who in good faith renders emergency services to a victim prior to or during the evacuation or extrication of the victim, shall be liable for any civil damages as a result of any acts or omissions by such person in rendering such emergency services.

For the purposes of this section, “emergency services” includes, but is not limited to, first aid and medical services, rescue procedures, and transportation or other related activities necessary to insure the safety of the victim who is the object of the search or rescue operation.