EXTREMELY URGENT!!!!!!!! PLEASE HELP!!!!!! QUICK RESPONSES PLEASE!!!!!!!?

So, in a long time short, my older sister is really mad at my younger sister (reason being, too long to type), she was telling me she was going to use a knife on her saying " I am going to make her life a living hell" and "When she walks through the door, when she gets home from school, I'm going to stab her with this knife, I have it right here." as she thumped it up against the wall near the bathroom. I have locked myself in the bathroom ever since those first words came out of her mouth about the knife, I am scared because I don't know if she was intending to stab me too.