Yahweh has accomplished his wrath, he has poured out his fierce anger; He has kindled a fire in Zion, which has devoured the foundations of it.
"It is because of the sins of her prophets .. and her priests"  (Lamentations 4:13a).  This should be read, "because of the sins even of her prophets and priests."  It was the wickedness of Israel's godless kings and of the people as a whole that brought on their destruction; and the thought here is that the very last vestige of the people's righteousness, the last repository of any righteousness, even the prophets and priests were corrupted.