How would you have handled this situation?

Woman and daughter are legal immigrants, living in America. they are from Somalia. mother speaks just fair English. she calls the police about her unruly 15 year old daughter. i arrive and the woman tells me her daughter constantly runs away from home, by escaping through her bedroom window. her daughter was not home and i began to make a police report. about ten minutes later, her daughter walks in the front door. at first, i started to arrest her as an unruly child. i changed my mind, once i heard her story. her daughter tells me the reason she runs away. its not a boyfriend…..its the beatings given to her by her mother. i then called for a female officer to meet me at this address. the female officer raised the girls shirt to reveil bruise marks on her back. the marks resembled the round end of a spoon. i looked around the house and located a 10” wooden spoon on the kitchen table. i compared the spoon to the marks on the girls back and it matched. i took photos of her injuries. what should have been my next action to take?