Naptime Episodes

Just recently my 2 year old has been waking from her naps with extreme violent episodes. She is an aggressive child, but doesn't intentionally hurt others. She woke from her nap the other day kicking and screaming. I went to console her, and she attacked me. She left scratches on my face and drew blood. Freaked out for about 15 minutes, snuggled up in my arms, and went back to sleep. When she woke up about an hour later, she was just as pleasant. It is kind of eerie. It seems like she wasn't awake. The other times it has happened it took me a bit to wake her, but when she came to, she was just fine. She was born very premature. I was just curious if anyone else has dealt with anything like this. It kind of freaks me out.