it just, like, they are always calling me and it makes me want to do it. >> it's just this new rage amongst girls is this girl fighting. and they feel like they have to prove something to fight. i just hate to see girls fighting, taking it to that level. >> but on march 25th, 2011, sierra decides to do just that when she agrees to fight a female classmate in the woods after school. >> i had a group of people. she had a group of people. when i showed up there first and there was already a lot of people there, like double the amount of people that i had with me, i was just -- i don't know -- shocked that there was really that many people that knew about it. and a lot of them were older people, too, like high school. i was like, why are all these people here? >> wait. get closer. >> with dozens of kids egging them on, sierra and the other student begin to fight. sierra's friend captures the disturbing scene on her iphone. >> i was so into it that i