California Code, Penal Code - PEN § 409.5

(a) Whenever a menace to the public health or safety is created by a calamity including a flood, storm, fire, earthquake, explosion, accident, or other disaster, officers of the Department of the California Highway Patrol, police departments, marshal's office or sheriff's office, an officer or employee of the Department of Forestry and Fire Protection designated a peace officer by subdivision (g) of Section 830.2, an officer or employee of the Department of Parks and Recreation designated a peace officer by subdivision (f) of Section 830.2, an officer or employee of the Department of Fish and Wildlife designated a peace officer under subdivision (e) of Section 830.2, and a publicly employed full-time lifeguard or publicly employed full-time marine safety officer while acting in a supervisory position in the performance of their official duties, may close the area where the menace exists for the duration of the menace by means of ropes, markers, or guards to any and all persons not authorized by the lifeguard or officer to enter or remain within the enclosed area. If the calamity creates an immediate menace to the public health, the local health officer may close the area where the menace exists pursuant to the conditions set forth in this section.

(b) Officers of the Department of the California Highway Patrol, police departments, marshal's office or sheriff's office, officers of the Department of Fish and Wildlife designated as peace officers by subdivision (e) of Section 830.2, or officers of the Department of Forestry and Fire Protection designated as peace officers by subdivision (g) of Section 830.2 may close the immediate area surrounding any emergency field command post or any other command post activated for the purpose of abating any calamity enumerated in this section or any riot or other civil disturbance to any and all unauthorized persons pursuant to the conditions set forth in this section whether or not the field command post or other command post is located near the actual calamity or riot or other civil disturbance.

(c) An unauthorized person who willfully and knowingly enters an area closed pursuant to subdivision (a) or (b) and who willfully remains within the area after receiving notice to evacuate or leave shall be guilty of a misdemeanor.

(d) This section shall not prevent a duly authorized representative of a news service, newspaper, or radio or television station or network from entering the areas closed pursuant to this section.

(e) This section shall not prevent an individual who holds a valid livestock pass identification document, pursuant to Section 2350 of the Food and Agricultural Code, from entering the areas closed pursuant to this section, unless a peace officer identified in subdivision (a) finds that the disaster is of such a nature that it would be unsafe for the documentholder to enter or that the presence of the documentholder would interfere with disaster response.