Lamentations 4:19 (ESV)

19 Our pursuers were swifter than the eagles in the heavens; they chased us on the mountains; they lay in wait for us in the wilderness.

Some people would try to flee from the city in the time when it was under siege. When the city finally fell, people also fled, either in the direction of the mountains or of the desert. But all attempts at flight were useless: the Babylonians had set up guards everywhere and were quicker than “eagles.” Jeremiah might be thinking of Deuteronomy 28:49 here: “The Lord will bring a nation against you from far away, from the ends of the earth, like an eagle swooping down.”