It may seem strange, but no one was injured in that fire.

Literal

Strange [quotative-に] thought may [but-が], that fire [with-で] no-one injury [object-を] did-not.

不思議に思われるかもしれないが = 'it may seem strange, but.' 思われる is the passive/potential of 思う. 誰も怪我をしなかった = 'nobody was hurt.'