Albert Barnes Commentary 2 Kings 19:18

"and have cast their gods into the fire; for they were no gods, but the work of men`s hands, wood and stone; therefore they have destroyed them." — 2 Kings 19:18 (ASV)

Have cast their gods into the fire - In general, the Assyrians carried off the images of the gods from the temples of the conquered nations and deposited them in their own shrines, as both trophies of victory and proof of the superiority of the Assyrian deities over those of their enemies. But sometimes the gods are said to have been “destroyed” or “burnt with fire,” which was probably done when the idols were of crude workmanship or coarse material, and when it was inconvenient to encumber an army with spoils so weighty and difficult to transport.