California Code, Government Code - GOV § 53021

(a) A national or local emergency created by military attack or sabotage.

(b) Providing adequate national or local defense.

(c) A local emergency, as defined in subdivision (c) of Section 8558.

(d) Before one local agency may respond to a request for material fire protection or aid pursuant to this article the requesting agency must have primary fire protection by an organized fire department pursuant to law, and the request for aid must come from the chief or other authorized agent of such requesting agency.

Notwithstanding budget limitations and restrictions imposed by law, except limitations imposed by the Constitution, all such services performed or expenditures made are payable from any funds of the public agency rendering the services or making the expenditure upon the adoption of a resolution by the governing body of that agency determining that the services were performed or the expenditures were made in connection with such an emergency and designating the fund or funds from which the obligation is to be paid.