Albert Barnes Commentary 2 Kings 17:25

"And so it was, at the beginning of their dwelling there, that they feared not Jehovah: therefore Jehovah sent lions among them, which killed some of them." — 2 Kings 17:25 (ASV)

The depopulation of the country, which was not fully remedied by the influx of foreigners, had the natural consequence of causing wild animals to multiply and become bolder. A number of these animals had probably always lurked in the thicket along the Jordan River (Jeremiah 49:19; Jeremiah 50:44), and now they ventured into the hill country and perhaps even into the cities.

The colonists regarded their suffering from the lions as a judgment upon them from “the god of the land” (2 Kings 17:26; compare 1 Kings 20:23).