Cal. Business and Professions Code § 7583.12

(a) An employee of a licensee shall not carry or use a firearm unless the employee has in their possession both of the following: (1) A valid guard registration card issued pursuant to this chapter. (2) A valid firearm qualification card issued pursuant to this chapter. (b) An employee of a licensee may carry or use a firearm while working as a security guard or security patrolperson pending receipt of a firearm qualification card if the employee has been approved by the bureau and carries on their person a hardcopy printout of the bureau’s approval from the bureau’s internet website and a valid picture identification. (c) Paragraph (2) of subdivision (a) and subdivision (b) shall not apply to a duly appointed peace officer, as defined in Chapter 4.5 (commencing with Section 830) of Title 3 of Part 2 of the Penal Code, who meets all of the following: (1) The peace officer has successfully completed a course of study in the use of firearms. (2) The peace officer is authorized to carry a concealed firearm in the course and scope of their employment pursuant to Article 2 (commencing with Section 25450) of Chapter 2 of Division 5 of Title 4 of Part 6 of the Penal Code. (3) The peace officer has proof that they have applied to the bureau for a firearm qualification card. (d) (1) This section shall not apply to a duly appointed peace officer, as defined in Chapter 4.5 (commencing with Section 830) of Title 3 of Part 2 of the Penal Code, or a federal qualified law enforcement officer, as defined in Section 926B of Title 18 of the United States Code, who has written approval from their primary employer, as defined in paragraph (2) of subdivision (h) of Section 7583.9, to carry a firearm while working as a security guard. (2) A peace officer exempt under this subdivision shall carry on their person a letter of approval from their primary employer authorizing the peace officer to carry a firearm while working as a security guard.