good evening and welcome to a special hour of coverage, lester holt is in our new york studios, and our team is here in what must be tonight the saddest place on earth. newtown, connecticut. it was here in the even smaller hamlet called sandy hook at the local elementary school grades k through 4, that a young man heavily armed wearing black, started firing today. he killed 20 children and six adults before taking his own life. and this is one of two crime scenes in this same town tonight. this small new england town at the northern edge of the new york suburbs and the middle of the connecticut countryside, and all decorated for christmas has just been destroyed. everybody in this country, from the president of the united states on down has the same question tonight. how could someone have done this, and how could someone have