Nobody is really dying, it was simply made up in order to scare the contestants and try to get them to give up, We never actually see Tommy die, and the cameraman running on with blood on him was probably staged, why do you think they didn't let anyone get close to him?
- Or else it's intentional, and a way to get them to stay, and introduce some drama into it for audiences. There's no voting, no challenges, or anything else, besides "Survive".
If the show is picked up for a second season, it will focus on the survivors being back in the real world, trying to deal with what happened to them as well as to try and learn the truth about who was behind what happened to them in the first season and why.
The contestants are essentially bait, sent to draw out whatever it is is lurking in the area and kept ignorant in order to keep their behavior and reactions as natural as possible. The crew is there to document everything.
And when questioned about it, she'll say that she had no other choice to kill him.