Actually, I'm quite embarrassed to say that my 14-year old knew about it before I did. She came to me in tears because she LOVES Paris and was devastated about what was happening. I went to FoxNews and saw what was happening all while we were talking about the events. She and I talked for about an hour and then we spoke about it the next day. She knows it's real life and it happens. It makes her angry to see who is/was behind the attacks. But through her anger, she's glad that her daddy is able to do something about, taking a little bit more pride in his service to our country.
Meanwhile, my middle who is 11 knows what happened, understands that a lot of people died, but has no connection to them to grasp what really happened. If that makes sense.
Of course, my 2-year old doesn't know what's going on and I didn't bother to say anything in front of him, nor do I watch/read anything about it with him present.