Legal Question in Family Law in California

They will very likely lose custody of the child, and possibly criminal prosecution. More facts would be needed to really say.

The question lacks all the information needed to give a complete answer, nontheless I will do my best with what you've provided. If there is a current order establishing that the child is to remain in CA, then there is a violation of that order. You need to notify the police and provide a copy of the order to them so they can track down the child and return the child pursuant to any directives in the order. If there is no order in place and the parent fled with the child, you should report this to the police so they can help you locate the whereabouts of the child. You should also consider filing an ex parte motion with the court to get the child returned to CA and to your care.