I doubt this is the only fight that has occured. I'm sure a similar fight happened (involving "Katrina" students or not) at another high school and was not picked up on the AP wire. Unfortunately, some high school students don't give damn and could careless about anyone else's situation (they're teenagers). Its high school, do you think they would be given a grace period before a few got picked on??
All I see in the article is "displaced N.O. students got in a fight with other students." Nothing about the demographics of the school, nothing about the demographics of the school district, nothing about the school's location (surburbs vs. city), nothing about the income or race of the students that started the fight, nothing about what caused the fight (other than the can throwing incident - who knows what took place before), etc. It could have been over a girl for all I know.
That said, not enough info to come up with a conclusion.