Bruce had been studying in the library when the lights went out. It wasn't so unusual at first, it was quite common for him to start his revisions after class and look up and see the sun had gone down but this seemed unusual. As head boy he had a duty to keep order.
"No I don't think Professor Kilgrave will hold it against you if you're late considering the circumstances, but you really must stop crying. You three come away from the windows! Hufflepuff is this your off period, if not get to class!"