Tomorrow, when the war began (Tomorrow #1)

Seven Australian teenagers return from a camping trip in the bush to discover that their country has been invaded and they must hide to stay alive. When Ellie and her friends return from a camping trip in the Australian bush, they find things hideously wrong--their families are gone. Gradually they begin to comprehend that their country has been invaded and everyone in their town has been taken prisoner. As the reality of the situation hits them, they must make a decision--run and hide, give themselves up and be with their families, or fight back.