Night terrors are very common in children. They are usually caused by a lack of sleep, so making sure your daughter gets in a good nap should stop these. I know they're scary, but she isn't really awake during it. The best thing to do is just hold her or sit by her bed until it's over.
i had night terrors as a child, it was so scary even as a adult i pray never 2 hav them again. the best thing i can say 4 u 2 help her is 2 hold her, & talk 2 her, let her no u r there. i wish her the best!