In Argentina at most games the fans are only allowed to sit behind the goals. If they sit any closer they will try to kill each other. I used to know a guy who went down to Argentina to visit he girlfriend's family. While he was down there he asked if they could go to a match. Apparently the GF's Uncle took a deep breath, let it slowly and said "Yes we can go, but no women no children. When he went there were riot Police standing by.
I would guess you never hear on the international news because no care about South America.
I actually know quite a bit about Argentinian football. What you're describing was either a long time ago or not referring to the first division. The only match that would remotely come close to that would be a Boca Juniors VS River Plate match...
This was about a decade ago. I don't know what league, or where in the country it was. I have had a few other people tell similar stories from a few other people. But that was the one with the most detail. Though I am hearing this all second hand so sadly I can't verify it.
"The media" is implying that you're only familiar with the media from your country and/or what you find in the majorly English-speaking side of the internet I assume? When I think of football hooligans, England is probably the last one I think about.