We don't know much here but we do have a bit more info than on the two recent Asian incidents. The aircraft descended at a steady rate in a straight line for several minutes until it hit the ground. That says to me that it was under aerodynamic control but not under the pilots' control. So it didn't explode in flight, it probably wasn't hijacked, and relatively simple things like a single engine failure weren't the sole cause. And that the simple answer to the 'why didn't they/why did they' questions is probably that they couldn't, for reasons yet to be identified.
Of the recent events, the one it's most like is MH370 (which was of course a Boeing) - but this time we should have the recorders pretty quickly to find out what happened.
Last edited by Beanbag; 24th Mar 2015 at 15:17.
Reason: Correcting typo