>> ifill: barry rosenfeld, i started this by saying it was sadly familiar but shockingly different. do you agree with that? was this very different from everything we've seen before? >> well, it's... i guess i wouldn't say it's very different. it's not what the last couple of mass shootings have been, but it's a workplace violence incident. what makes it different is the twitter feed, the live broadcasting of it. i think that is just a sign of the times, that people are savvy with technology and had this technology been around 15 years ago, the columbine would have been on youtube just as quickly. if i could just go back the a comment that your last guest made, you know, the other place where i guess i would hope people would maybe feel some responsibility is when a post is put on facebook or on twitter that i'm a powder keg, maybe that's a place where friends or family could jump in or could say, what's this about? have you talked to somebody about this? i think there are other avenues other than the media necessarily or the government surveying our post. but there are some opportu