My son is just growing out of this - it does happen!!!
Couple of questions:
* is she talking?
* is she communicating in other ways?
* is there something that she really, really loves?
When Pip got more words, his playing nasty reduced quite significantly.
In the meantime, I worked with the CCC with some strategies. All the children (and Pip) were taught to say "Stop! I don't like it!" and to leave that person alone. It really was something to work with everyone. Also using the Hand (stop) sign to stop the behaviour. That's really worked too.
When he started being obsessed with his Thomas train & track, we thought we'd withhold Thomas if he wasn't good. But attention span of a 2-year old isn't great. So we draw a picture of a train on a whiteboard next to his name, and tell him that if he's a good boy and the train is there when we pick him up, then he gets to play. And the first couple of times we would explain what being "good" was - no biting, hitting or thumping allowed.
After he *wasn't* good a few times, and saw the train being wiped off the board, he learnt the consequence. And it's instant, so it's a cause & effect thing.
I hope some of this helps - it's a horrid thing, and I cried more than a few times, specially when some of the other mums would say "its hard when your child screams cause they get picked on" and studiously ignore me.
Hope it settles soon. Keep to the mantra "this soon will pass"

