火事 (kaji) means 'fire' as in an accidental fire or conflagration that destroys buildings or property. It is not the same as 'fire' for a campfire. For example, '隣の家で火事がありました' (There was a fire at the neighbor's house).

建物などが燃える災害です。キャンプの火とは違います。例：「火事になる」