Cal. Military and Veterans Code § 555

Such forces shall not be required to serve outside the boundaries of this state except: (a) Upon the request of the Governor of another state, the Governor of this state may, in their discretion, order any portion or all of such forces as may be then in actual service to assist the military or police forces of the other state who are actually engaged in defending the other state. These forces may be recalled by the Governor at their discretion. (b) Any organization, unit, or detachment of forces upon order of the officer in immediate command thereof, may continue in fresh pursuit of insurrectionists, saboteurs, enemies, or enemy forces beyond the borders of this state into another state until they are apprehended or captured by such organization, unit, or detachment or until the military or police forces of the other state or the forces of the United States have had reasonable opportunity to take up the pursuit or to apprehend or capture such persons if the other state shall have given authority by law for the pursuit by such forces of this state. Any person who is apprehended or captured in another state by an organization, unit, or detachment of the forces of this state shall without unnecessary delay be surrendered to the military or police forces of the state in which they are taken or to the United States. This surrender shall not constitute a waiver by this state of its rights to extradite or prosecute the person for any crime committed in this state. (c) Pursuant to the provisions of the National Defense Act of 1916, as amended, and such amendments as may be made thereto hereafter.