Looked up what happened to Bani Walid since the siege:

Witnesses said that many civilians are being killed by shelling, while houses were engulfed in flames. Many reports after the fall of the city claimed that pro-government militias used internationally prohibited weapons, white phosphorus bombs and nerve gas. Local people found the missiles militias used contaminated with white phosphorus. Used gas masks which were found on pro-government positions and the hospital reports say that civilians in Bani Walid have been bombed with gas.

This is what uncontrolled vengeance looks like. This is essentially a less total version of what happened to Diriyah about 200 years ago.