Family or Friends

Turning around you search the crowd for a suspicious looking person, but everybody is in a mask so you can not see their faces. As your panic grows you become very jumpy and paranoid. You go to the study to calm down a bit and assess the situation, but as you are about to open the door you notice that there is blood dripping down the wall and staining the rug. You freeze from fear, what is going on? Just then you hear another scream and a weak call for help. Surly this is enough evidence to call 911 right? But what if that provokes the murderer to kill more people, maybe you should try to stop them yourself before they kill anybody else?