It is hereby declared and agreed that loss as insured by this clause resulting from an interruption or interference with the business directly or indirectly arising from closure or evacuation of the whole or part of the premises by order of a competent public authority due to the operation of a peril insured by section ..... (material damage) of the policy or directly or indirectly arising from infectious or contagious disease occurring in the premises or from a threat of violent damage to the premises and/or injury to persons therein shall be deemed to be loss resulting from damage to property used by the insured at the premises.