ARENA, Wis. (AP) – Four people were injured in a stabbing after a fight broke out at a Halloween Party.   The stabbing happened early Sunday at a house in the town of Arena. Initially, authorities said three people went to the hospital with stab wounds. But WMTV-TV reports a fourth victim was discovered hours later.         Iowa County authorities say all four people received medical attention. Some injuries are serious, but not life-threatening.  Two men are in custody on unrelated charges Sunday night. They are being called persons of interest in the stabbing.  Authorities are still investigating.