Pretty damn disgusting.
It's baffling how some come to this country, legally or illegally, and then hang their own "previous" country's flag up like this is "their" claimed territory.

If your country was so great, why leave?
Why not leave the U.S. to go there?

Regardless, the school official should have called the cops.
Actually not sure if that would have "helped" the situation, or made it worse, but this sort of lawlessness and disrespect for public property is just plain abhorrent.