What shocking thing does Thomas notice? Provide an explanation of what occurred. Chapters 32-35

Thomas sees a Beetle Blade in the ivy and notices they have the word "WICKED" written on them. Minho says he is unaware of the words meaning. Thomas then notices a plaque in the wall that reads: WORLD IN CATASTROPHE: KILLZONE EXPERIMENT DEPARTMENT. Again, Minho has no idea what it means, but he notes that the plaques can be found all over the Maze.