You probably have the story from CNET, here:
http://www.cnet.com/news/cops-forcef...up-cell-phone/
The Daily Caller also ran with the story a couple of days ago, but they have the number of cops as 2, not 3, from what I see in google. Didn't read their story.
The notable thing is the 70-lb was violently subdued for 'failure to comply.' She had done no violence and threatened no violence. The police had been called to the school because the girl had refused to surrender a cell phone. They allegedly went to painful violence as their first response to the situation, with no dialog whatsoever.
This seems to me to reflect either an irrational habit of violence on the part of the officers, or perhaps a goal of physically punishing the girl, summarily, for her defiance. Either way, the potential for serious injury inherent in a forcible takedown, as well as the physical insult over a petty discipline issue, argue that such practices by the police come to a screeching halt. If the girl does not physically resist, there is no justification for physically assaulting her.