Not good. Now they are saying there was no word from anyone on board since it took off.
Nothing. No emergency beacon, no radio transmissions, no cell phone calls. The odds of that happening at cruising altitude due to mechanical is low I believe. Whatever it was it was catastrophic. Sad end for these people. 
Sounds a little like Helios Airways Flight 522. Yeah, I found that one trying to look up another one.
I recall a similar incident that happened here in the US some years ago, where a private jet crashed. In this case, there was a valve in the engine that was locked "open", which after it climbed to 20k, caused the entire crew and passengers, to pass out. Tried to look up the details of this flight, but haven't been lucky. Ran into Flight 522.