My son, who is now 10 did this as a baby and young toddler. I have no idea what caused it, but I could not wake him up. I just sat with him and talked to him and stroked and patted him until I could get him to lay back down. Once I could get him to lay back down, he usually settled back down and went back to sleep (even though he was actually asleep the whole time). He very rarely opened his eyes. When he did, it was usually to sleep walk, not because of night terrors.
Then, comes my daughter, now two and a half. There is absolutely no soothing her when she has one. She is also very violent when she has one. Unlike my son, she is usually wide-eyed and flailing about. She will scream, kick, hit, bite, whatever to get who ever is trying to sooth her away. She had one in the car that was so bad that I had to pull over and stop to try to get her to wake up. I was scared she would really hurt herself. With her, I just prepare myself for the "beating and biting" and do my best to restrain her and keep her from hurting herself. I also try to "talk her down" which is really hard when she just bit you so hard you are sure you are missing flesh, or she just gave you a black eye. This one really scares me. She too will sleep walk and has, on occassion, started knocking things over and about when in her way. Have talked to the doctor and know that I will just have to watch her like a hawk. Which is why she sleeps with me. I sure hope she grows out of it soon. :O) My son still sleep walks every so often. One morning about 5-5:30, he went out and let the chickens out of the hen house. How we figured this one out is 1) they were out and 2) he said he dreamed about hearing the chickens really loudly and thought they must be outside his bedroom window.
One thing I would definitely do is talk to you doctor about it. They will probably tell you there is nothing you can do about it, but make sure it is recorded in your child's chart. I say this because if sleep walking occurs with your child and they wander out of the house and God forbid, something should happen and the authorities are called, you have documentation showing your child's condition. This advice came from my doctor who told me he was glad I mentioned my son's sleep walking because of such a scenario as above happening with one of his patients in the past.
Other than that, just try to calm your daughter down and get her to "go back to sleep" for lack of better words. With you son, put a chain or slide bolt up high on every exterior door. You could try putting a child gate or two (stacked) across his door. That may keep him in his room.
I wish you much luck in this. It can be very trying. With my son, when he was a more active sleep walker, he would get up two or three times a night sometimes. Those were the nights that I didn't get much sleep.
Blessings,
L.