Then they just walked out in the middle of the interview without saying a word when it wasn't going well, leaving the other interviewers to continue without the

Then they just walked out in the middle of the interview without saying a word when it wasn't going well, leaving the other interviewers to continue without them. Then you should walk out as well. Explaining calmly but confidently why you are doing so, of course, to underscore the fact that you can still be a professional even when they are not. But either way -- the interview had clearly lost any purpose by that point, so the sooner everyone can cut their losses and move on, the better.