Choices:
1) React to defend your kid and/or call the cops and get pulled into a massive and expensive legal imbroglio.
or...
2) If the kid is not hurt leave as soon as you can and avoid large lawyer fees and hassle.
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imbroglio /ĭm-brōl′yō/
noun
A difficult or intricate situation; an entanglement.
A confused or complicated disagreement.
A confused heap; a tangle.