Hi Angie,
Yes unfortunately those events did happen :(
It was between bosnian and serbian fans.
Unfortunately because Australia is a relatively "young" country, often there are clashes between cultures that have nothing to do with "Australia" but more to do with the origin or country of imigration from these people. Ego's and cultural prejudice do have some impact, more so in the bigger cities where there are larger numbers of multiculturalism.
Thankfully this isn't what I would consider an "epic problem" within Australia, and I guess every multicultural country faces culture clashes. It is sad that things like this occur though :(