YA Horror book I read around 2006-2011 with evil witch and car crash towards the end

[Rebecca]

YA Horror book I read around 2006-2011 where there's a witch hunting a group of kids who are being killed off in increasingly horrifying ways and towards the end two of the final survivors get injured/killed in a car crash escaping the forest and the cover was really terrifying

[Kris]

Rebecca, what's the location - e.g., fantasy world, country, region, well-known city, small town?

Can you tell us more about the group of kids? Why is she hunting them?