Shilishi…”Question: In a case where the parents are abusing the children physically…..”
Since your statement says that the parents are abusing their children…without a doubt. Then to me this is a matter of life or death and thus everything should be done to remove the children immediately…regardless of where they are placed. The priority is a safe environment. If it’s with a secular or even non-Jewish family, then that is what needs to be done…a permanent home will be worked out later…
and Yes, the police should be called, then the Rav. In that order.