It's also damn suspicious the psycho vamps got themselves killed so easy. Are you really gonna let it slip you live nearby then start threatening and attacking humans?
Remember, most vamps see humans as a food source, not a threat. They see mainstreaming as a bad idea. They don't think the humans can do anything to harm them, since vamps are so uber powerful ... as long as the sun isn't out. (the vamp phrase for dying is "meeting the sun")
They're trying to get Bill. And they'll do anything it takes. They have no clue what the world is like, other than their own little bubble.