California Code, Business and Professions Code - BPC § 7590.3

(a) A person employed exclusively and regularly by any employer who does not provide contract alarm services for other entities or persons, in connection with the affairs of that employer only and where there exists an employer-employee relationship.  A person so employed shall at no time carry or use any deadly weapon in the performance of his or her duties.

(b) An officer or employee of the United States of America, or of this state or a political subdivision thereof, while the officer or employee is engaged in the performance of his or her official duties, including uniformed peace officers employed part time by a public agency pursuant to a written agreement between a chief of police or sheriff and the public agency.

(c) Patrol special police officers appointed by the police commission of any city, county, or city and county under the express terms of its charter.

(d) A licensed private patrol operator or any employee of a licensed private patrol operator who is employed as a security guard, security officer, or street patrol person as defined in Section 7582.1 and who is employed to respond to alarm systems.