2 sentences

1. 这起火灾被认定为蓄意纵火。

   zhè qǐ huǒ​zāi bèi rèn​dìng wéi xù​yì zòng​huǒ.

   This fire was determined to be a case of deliberate arson.

   Source: Dong Chinese Dictionary

2. 那场森林大火是有人蓄意纵火引起的。

   nà cháng sēn​lín dà​huǒ shì yǒu rén xù​yì zòng​huǒ yǐn​qǐ de.

   That forest fire was caused by deliberate arson.

   Source: Dong Chinese Dictionary