"
Based on the best information we have to date, what our assessment is as of the present is in fact what began spontaneously in Benghazi as a reaction to what had transpired some hours earlier in Cairo where, of course, as you know, there was a violent protest outside of our embassy--sparked by this hateful video. But soon after that spontaneous protest began outside of our consulate in Benghazi, we believe that it looks like extremist elements, individuals, joined in that-- in that effort with heavy weapons of the sort that are, unfortunately, readily now available in Libya post-revolution. And that it spun from there into something much, much more violent." "We do not-- we do not have information
at present that leads us to conclude that this was premeditated or preplanned.""I think it's clear that there were extremist elements that joined in and escalated the violence.
Whether they were al Qaeda affiliates, whether they were Libyan-based extremists or al Qaeda itself I think is one of the things we'll have to determine."
http://en.wikipedia.org/wiki/Benghazi_attack