Cal. Bus. & Prof. Code § 7583.12

(a) No employee of a licensee shall carry or use a firearm unless the employee has in his or her 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 he or she has been approved by the bureau and carries on his or her person a hardcopy printout of the bureau’s approval from the bureau’s Internet Web site and a valid picture identification.

(d) 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) He or she has successfully completed a course of study in the use of firearms. (2) He or she is authorized to carry a concealed firearm in the course and scope of his or her 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) He or she has proof that he or she has applied to the bureau for a firearm qualification card.

(e) (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, who has written approval from his or her primary employer, as defined in paragraph (2) of subdivision (i) of Section 7583.9, to carry a firearm while working as a security guard or security officer.

(2) A peace officer exempt under this subdivision shall carry on his or her person a letter of approval from his or her primary employer authorizing him or her to carry a firearm while working as a security guard or security officer.