I've never been to Marseille but it has a reputation of being where the mafia is, gang clashes and all, and where there are more of the poor suburbs than Paris. It's also where we see more frequently news of groups of asshole kids using mortars on cops - Paris is not far behind, especially during riots like this one, but around Marseille it just happens sometimes when a kid gets shot because of gang rivalries and cops response with raids blasting doors in apartment buildings because they decided someone lived there. It's also where guns get around, which it doesn't much in Paris or its poorer suburbs, hence the gang problem. A few years ago there was also an incident where firefighters got ambushed there, that one was pretty bad.

I figure actually living there is not close at all to this reputation, but gang shit does happen there.