I'm trying to come up with a word to describe what happens in cartoons (and probably real life) when a traumatic event leads to a group of ordinary people (usually children) to fend for themselves. They then form a new society resembling a dictatorship ruled by bullies.
I'd call it a "Lord of the Flies situation". Lord of the Flies is a novel about some school kids on a field trip that are shipwrecked and wash up on an island with no adults, and form just what you described: a spontaneous, cruel society of neglected people.
I think nearly all somewhat-educated adult English speakers would understand exactly what you're talking about; we all had to read it in high school.