Happened in America recently, 2005 Hurricane Katrina:

https://www.npr.org/templates/story/story.php?storyId=506379...

As of right now, it might be upside down if you're stuck in Syria or Yemen?

In the US, you might recall the outcome of the Rodney King verdict as an example.

Pretty much any natural disaster.

The quakes in Mexico and the hurricanes that hit the gulf region islands and countries last year spring to mind.

Areas where natural disasters have hit have been very problematic, and the US has had large scale riots. Houston seems to be the exception. Local area reversions to anarchy can get you shot.

Right now the best examples are Venezuela and Zimbabwe.

Tornado's are frequently a thing. Emergency services become easily overloaded.

Paris train attacks, hurricanes in Florida, the machete attacks in London...

Puerto Rico?