Charles Ellicott Commentary Lamentations 4:15

"Depart ye, they cried unto them, Unclean! depart, depart, touch not! When they fled away and wandered, men said among the nations, They shall no more sojourn [here]." — Lamentations 4:15 (ASV)

They cried to them — that is, these, as they passed, cried to the blood-stained priests. The cry “unclean” was that uttered by the leper as a warning to those he met (Leviticus 13:45). Here it comes from those whom they meet, and who start back in their fear of defilement.

When they fled away. — The words seem to refer to some lost facts, like those suggested by Lamentations 4:14: the murderers fleeing from their own countrymen, and finding themselves equally abhorred among the heathen.