What makes Huck begin to think something has gone wrong when Aunt Sally catches him in the cellar?

Huck sees fifteen armed farmers are sitting in the house waiting for the robbers to come during the night of the escape. He knows something has not gone as planned. Huck is frightened for their safety when he slips out the window and tells Tom they must leave immediately or they will be shot. Tom gets very excited when he hears about how many people came to catch them.