Is it possible for my baby to actually crawl before she sits up?

My daughter is 8 months today and I was wondering, is it really possible for her to start crawling before she sits up? She can sit up on her own until she realizes it or reaches for something. However, lately she is getting up on her hands and knees and she scoots forward and backward. She is getting really close to crawling but seems to have no interest in sitting. She loves to roll around all day and play that way.