We have a new dog, and when kids play (specifically when they run around) she kind of gets nuts.?

It seems to me like she's just playing, but she gets her mouth involved (she is a 10 month old boxer/pit mix) and though she hasn't drawn blood, she has left scratches from her teeth... though this has only happened a few times to kids and once to me. Two of these times the children have screamed, which seemed to possibly make her more aggressive... she would jump higher and snap with her jaws. She is a super friendly dog, and seems to enjoy kids crawling on her, playing with her in all kinds of manner... she is not dog aggressive or aggressive in any other way except when this happens. Is there any way to curb the behavior, or do I just make sure that she's not around when kids are running around?