Ainda não estou totalmente convencido, mas minha tendência é concordar com a segunda opção (incêndio decorrente de tumulto)
Nesse caso, alguns dos termos usados são:
riot, civil commotion or civil disturbance (o "civil" aí é para excluir atos de guerra ou terrorismo)
Fire policies generally contain a condition that the insurer will not be liable if the fire is caused by riot, civil disturbances, war and explosions. ...
www.scribd.com/doc/35710754/Fire-Insurance - Cached
Some fire insurance policies may also exclude fires caused by riots and civil commotion.
Riot usually refers to a gathering of three or more people that results in the use of force or violence against individuals or property. Damage caused to the insured property due to riot is covered under this peril. Coverage includes direct loss caused by striking employees whether a riot occurs or not. Civil commotion can be defined as an uprising or disturbance by a large number of people. As with riot, damage caused to the insured property due to such an uprising would be covered under this peril.
http://www.wjwheeler.com/insurance_faq/199f019.htm
The translation workplace 
peer agreement (net): +2
