Lord Voldemort enters Hogwarts under a disguise. His death eaters follow him, also in disguise. He orders them to destroy anybody they find, until he summons them to his side. He proceeds to go to the Headmaster's study, and murders Dumbledore. He then sits in the Headmaster's seat and scribbles a note on a piece of parchment, addressing the letter to "The Boy Who Lived, Diagon Alley". He whistles once and a pitch black owl appears next to him. He ties the parchment to the owl's leg and sends him on his way.