With my particular background, I would want to know exactly what the mechanism was. That would include what kind of weights, machine, during what portion of movement did the injury occur, and so on. This would give me a good idea what the likely injuries are, but not necessarily what injury was suffered. I would then try to get into contact with whomever the legal guardian is, obtain consent to treat, assess, and treat appropriately, including transport to an appropriate facility. As stated above, without much information, not much beyond what has been said can be provided.
From what VERY limited info there is, I have an idea about what happened, but absent specifics, that's all I got. Specific field treatment isn't going to vary much except perhaps in destination decision.