How does Katniss know something is wrong when she is looking for Rue?

Answer 1

Before going to blow up the food, Katniss and Rue came up with signals for each other. The signals were to tell each other that they were okay, and that they would be back soon. Rue was supposed to signal once she had lit every fire, and Katniss was supposed to signal once she had blown up the food.

Katniss blew up the food and she triumphantly signaled Rue. But when she signaled, Rue did not signal back. Rue was supposed to be done her duty before Katniss. When Rue did not signal back, that was the point when Katniss knew something was wrong.

Katniss tried to signal while looking for Rue in the woods, but there was no reply. Katniss found one unlit fire, and then she really knew soemthing was wrong. Eventually Rue screamed her name. Katniss found her caught in a netting trap beside one of the fires she was supposed to light. Katniss freed her, and they were getting ready to leave. But it was too late. Marvel, one of the Career tributes, speared Rue through the stomach.

Katniss killed Marvel, then sang to Rue until she died. But the point when Katniss knew something was up, was when she saw one of the fires unlit, and when Rue wasn't replying to her signal.