(a) A responsible party, as defined in Section 8670.3, shall be absolutely liable without regard to fault for any damages incurred by any injured person that arise out of, or are caused by, a spill. (b) A responsible party is not liable to an injured person under this section for any of the following: (1) Damages, other than costs of removal incurred by the state or a local government, caused solely by any act of war, hostilities, civil war, or insurrection or by an unanticipated grave natural disaster