D.L.
My oldest son did the very same thing and when the doctors told me it was normal I videotaped it to prove to her it was not normal. He would wake screaming for water at the top of his lungs and his eyes were wide open but he never looked at us. He always had his hands in the air screaming for water and when I tried to give it to him he didn't even act like he could see the water. The sound of voices only made him scream louder and kick and wave his arms around harder. When I showed it to the doctor she said yes that looks like a night terror (it also lasted around 20 minutes).
She told us that night terrors are not dreams like many people think. Night terrors are common in children and it is how the body reacts when the brain gets stuck between two stages of sleep. Nothing more than that. As crazy as she sounded I think she was right. He hasn't had one in several years.
One thing I noticed though was they happened more offten to my son when he had a stressful day. I tried changing my dicipline a bit and using more calm stern direction rather than getting him in trouble. I think that had something to do with it too because sometimes it happened more than once a night and when I mentioned that to the doctor she said if that is hapening it sounds more behavioral. A few months after that doctor visit they quit all together. I tried not to give him the oppertunity to get into too much trouble, be too busy, or get too tired in one day.