Yes, when there is nothing else that can be done. When dialogue and years of protest doesn't work, violence is the only solution.
Don't be naive. There will always be casuality in a conflict. And the rioters are (at least usually) informed and intelligent, they don't attack the kind of social classes that can't do anything about it.
Sorry about that
Those who attack firemen are actually the young ones, that are mostly following without being too informed. You will usually see people tell them to calm down on the spot. Even in huge protest.
There are different classes of people that we must help. Sadly, not all classes are informed on every subjects of the others. Here, this is the riot of the popular class which is sometimes uninformed on the LGBTQ+ problematics. This is normal and the left is aware of that. That doesn't mean that we must not help those people or not give them our support when they face systemic repression. All progressive fights are worthy.