AFAIK there is no gun registration law in LA or NO.
LA in general has been pretty good on the gun issue up until now, but of course with a leftist Democratic administration at both the local and state levels you can't count on any Constitutional right being safe.
I hope that any NO citizen who is harmed or loses significant property because he or she was deprived of their legally owned firearm will sue the city and state, and the mayor and governor personally. I don't know if that's legally possible, but if it isn't it should be. Confiscating a person's gun in that chaotic situation is equivalent to imposing a death sentence on him or her.
The law suits need to start. Criminal investigations should also be pushed. Unfortunately, it will take mob action to scare the establishment to the correct action, i.e. as does the race baiters and hate crime mongers do to get their way.
And what about the financial loss? Firearms are not cheap. Whoever took them needs to either return them or financially compensate the owners. Then again, if 2nd amendment rights can be tramples, so can search and seizure rights. These people will likely never see their weapons or any compensation. It will be because of the state of emergency.