This is a fairly complicated set of laws.  There are three types of  “gun violence restraining orders” possible.

(1) A temporary emergency (by police), (2) ex parte (by family member or police) and (3) after notice and hearing (for one year term).  There is also a penalty if someone makes a false petition, e.g. a misdemeanor penalty.

There are judicial council forms for this: http://www.courts.ca.gov/33683.htm