Can father claim visitation if he lets his children leave?

Children went for visitation with Dad. Youngest (10)did not want to be with Dad. Dad was pulling him out of car by arms and legs while son was screaming. Daughter (16) was afraid for her brother..they both ran back to car, said goodbye to Dad and drove away. He did not stop them but demanded the children return because it was his visitation period. Can mom be in trouble for interfering with custody when they were at dads residence and he left them leave. Children came back to mom but she did not request the children come back. She offered for dad to come and get them but he refused and demanded mom bring children to him or he would call the police.