Anyone know the name for a scifi/horror movie? Please help!?

I watch this movie on dvd sometimes around 2004, I dont know when it actually came out but the quality was good. I think it was a scary movie. I only remember some parts about the movie, so Im dying to know what movie it was. I remember that the leading actor is a female. I remember that it was somewhere in the rural area with fields of crop. She was on a school bus with friends on a school trip. Something ped by her and she saw a word or something that gave her a sinister feelings that something bad is going to happen.I also remember that there was also some kind of during creatures after them. The bus was destroy or does not function anymore, so they got off and ran into the field. That is all I remember. I really want to know what movie it was, please help me. Thank you.