Last I heard the aircraft was cruising at 35,000ft when radar contact was lost. If true that is indicitive of something not good.
“Radar contact was lost” sounds like the thing blew up.
According to how radar works that would mean that the plane was there and then in the next split second it wasn't.
That would mean the plane catastrophically blew up and disintegrated in the blink of an eye. Quite possibly this is a TERRORIST caused act.