2 Peter 2:4

For if God spared not the angels that sinned. In order to show that judgments on these wicked teachers are sure, Peter cites examples. Even angels when they sinned were subjected to punishment.

But cast [them] down to hell. The sinning angels were cast out of heaven. The word rendered "hell" is not Gehenna, but Tartarus, a Greek term used for the place of future punishment.

Delivered [them] into chains of darkness. "Pits of darkness" (Revised Version); possibly dungeons of darkness gives the idea. Compare Jude 1:6 Both passages point to a time when angels sinned, fell, and thus became angels of darkness.
Copyright information for PNT