I've locked down all the usernames involved in this and have put the board into MBA mode - I suggest you keep it that way for a while at least, until this settles down.
I've also banned those usernames by email, so that they can't register new names and come back later, using those addresses at least.
You can see which are the names I've locked down (they all have an email ban), so you can delete their posts quickly, if they've made replies to existing threads. It won't however delete any posts which started threads, so you'll have to do those separately.