Dial 999 or 911 - ask for "fire"
it is better to get rid of the mad malks in the hall before the end of that mission, but shooting them from the balcony is OK as a solution.
the shotgun can move the problems away without you getting ignited, but there are other solutions.
I did it with a fire-axe and celerity 5 a few days back and that works quite well too.
it is a good idea to heal up along the route, but watch out for being attacked from the rear once you get to the balcony.