what would you do if this was your children?

(want to start out by saying yes I took care of the situation and legal things are being done) but wanted views from others mom's and dad oossibly.what would u do if your daughter came home next day from her father's and had bruises on her shoulder fingerprints on arm and bruises on side? telling you her dad got mad because her and her brother was laughing during dinner.grabbed her and pulled her by arm picked her up and threw her in bathroom to shower.then meanwhile took your 6 year old son in his room shut light off and shut door( son is scared of dark) then 2nd night that week daughter comes home scared quiet not wanting to talk and brother tells me dad hit her.get home and possibly 12 13 hours later still hand print on her leg bright red? what would u do!