California Code, Penal Code - PEN § 27882

(1) The firearm is voluntarily and temporarily transferred to another person who is 18 years of age or older for safekeeping to prevent it from being accessed or used to attempt suicide by the transferor or another person that may gain access to it in the transferor's household.

(2) The transferee does not use the firearm for any purpose and, except when transporting the firearm to the transferee's residence or when returning it to the transferor, keeps the firearm unloaded and securely stored, as defined in Section 25145, in the transferee's residence.

(3) The duration of the loan is limited to that amount of time reasonably necessary to prevent the harm described in paragraph (1).

(4) The individual receiving the firearm is not prohibited by state or federal law from possessing, receiving, owning, or purchasing a firearm.

(b)(1) If a firearm that has been transferred pursuant to this section cannot be returned to the owner because the owner is prohibited from possessing a firearm, the person in possession of the firearm shall deliver the firearm to a law enforcement agency without delay.

(2) Section 27545 does not apply to the transfer of a firearm to a law enforcement agency pursuant to this subdivision.  This section does not authorize the possession of a firearm by any person prohibited from possessing a firearm pursuant to any other law.