California Code, Code of Civil Procedure - CCP § 700.060

(a) To levy upon goods in the possession of a bailee (as defined in Section 7102 of the Commercial Code) other than one who has issued a negotiable document of title therefor, the levying officer shall personally serve a copy of the writ of execution and a notice of levy on the bailee.

(b) If the goods described in subdivision (a) are subject to a security interest, the levying officer shall, if so instructed by the judgment creditor, serve a copy of the writ of execution and a notice of levy on the secured party. Service shall be made personally or by mail.