Charles Ellicott Commentary Ezekiel 33:27

"Thus shalt thou say unto them, Thus saith the Lord Jehovah: As I live, surely they that are in the waste places shall fall by the sword; and him that is in the open field will I give to the beasts to be devoured; and they that are in the strongholds and in the caves shall die of the pestilence." — Ezekiel 33:27 (ASV)

In the forts —is rather, in the natural strongholds in which the land abounded.