This is a topic that came up here recently, and one that might seem a little tricky; aren't most articles in sources like Academic Search going to be about the U.S.? Well, actually there is often more than you might think, it's just a case of fishing around till you find it. First I did a search in Academic Search, simply france gang violence teen, but that only got one article, and not a very helpful one. No problem, just reword the search, to gang violence france. That got much better results, and highlights a basic rule of searching: if your results are few, broaden out your search.
Another rule of thumb is to bear in mind that no one database is going to have it all, so you might want to try something different. In this case, one source I would go to would be Lexis, which has a section of foreign newspapers in English. You might also want to look at our Criminal Justice guide.