How to control small black female dog aggression problem.?

I live in a hostel and a small black dog has taken residence in front of my room. She has been docile all this while but recently has started showing aggression towards other girls on my floor. A dog who has been sweet and friendly has turned into a classic growler! I would love some help to fathom and solve this because the general attitude towards dogs on campus is very negative and if she continues she will meet a bad end thanks to the community out here.