Oops is too mild a word

Seems they're ascribing an explosion in a Shi'a mosque in Iraq that killed a dozen people and injured nearly two hundred as, possibly, an 'accident' and that "ammunition kept at the Shohada mosque for the past five years, since an exhibition commemorating the 1980-88 war with Iraq, could have caused the explosion."

Rico says first off, why an 'exhibition' like that in a mosque, and, if so, why live ammunition?