Either the plane:
Disintegrated abruptly in flight as a catastrophic cabin systems failure( possible).
Was destroyed either as an act of terrorism or by some other man made or natural event. Could have been bb'd by a meteorite for all we know.
Or suffered a gradual depressurisation accident that incapacited everyone befor anyone could react.

Either way the chance of survivors is frankly non existent, absenting an act of God.
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I don't do dumb & helpless.