Ruptured appendix, hospital denies care

My son had severe pain one evening, and was up all night with it. In the morning he called 911 to get an EMT to come and take him to the hospital. We requested hospital A, but the ambulance drivers said they had to go to hospital B because it was closer. In fact hospital B was 7 miles further than hospital A which IS the closest hospital to us.

At hospital B, Son was triaged and told to sit in the waiting room. 3 1/2 hours later, I called the hospital to check on him. The hospital told me he had been discharged. So I called him to see what they said about his pain. He was still sitting in the waiting room, believing he was going to be taken care of. Around this time, another patient in the waiting room began harassing him, trying to provoke a fight. After sitting for 6 hours, Son got up and left the hospital.

At 11 my daughter arrived and took him to hospital A. There, he was seen and tests were begun within 2 hours. His appendix had ruptured and it was stuck on his liver.

Can he file a claim against hospital B for negligence?