The absolute destruction of Jerusalem is presented through a vivid metaphor of a collapsing wall [רש"י, רד"ק, ביאור שטיינזלץ]. The ruin unfolds in three distinct, gradual stages [מצודת ציון, מלבי"ם]. First, the city is breached; its defenses crumble, and it loses its structural wholeness. Next comes a complete collapse, as the structure falls entirely to the ground [מצודת דוד, ביאור שטיינזלץ]. In the final stage, the upper sections are so thoroughly destroyed that no trace remains, leaving only the bare foundations exposed [מלבי"ם, מצודת דוד].
This vivid imagery might leave the false impression that only physical buildings will suffer while the inhabitants escape safely. However, the destruction extends directly to the people [מלבי"ם]. The false prophets, who metaphorically covered the weak wall with useless plaster, will all be killed inside Jerusalem as it falls. Not a single one will escape [רד"ק, ביאור שטיינזלץ]. Conceptually, this means that the moment the enemy arrives and shatters the illusions of their false prophecies, the prophets themselves will meet their end [מצודת דוד].
Ultimately, this devastating ruin serves a greater purpose. Through the disaster, the people will be forced to recognize God's power. The events will prove that He is faithful to deliver justice and punish those who sin [מצודת דוד].