I don't think anyone really knows for sure right now. There is a TON of misinformation and wild speculation going on right now. Mostly, everyone is still so in shock from these attacks that no one really knows what's going on right now. The assailants are dead, that's all we know for sure. In the next day or so we'll probably start having a better picture of what really happen. Everyone (including the national news channels) are jumping on the blame ISIS bandwagon right now, since they have been in the news lately. But Al Queda is still a thing. Just give it a few days and let the shock and jumping to conclusions phase be over with, and then investigators will get to the bottom of this.