my friend is cutting herself and others r encouraging her. what to do?

[Phay D]

she is a nice person with a screwed-up backround. she isn't depressed and every one knos it- she does it 4 attention and she gets it. she has two groups she hangs around- my group and the other group. the other group encourages her and do it to themselves and my group pay too much attention to her when she does so. today she brought a knife to school and added another cut to her wrist then she said she was going to cut aross her belly when she got home.
she started this after seeing my own arm with scars all over it and i don't kno what to say or to do- i am not emo its just wat i did when i was bullied in grade five.