As others have said, it was NOT dark. Sunrise at local time was 5:15 AM and the aircraft lost contact at around 6:17 AM.
That's not exactly "dark".
There are air disasters where the wreckage was not located for 24-48 hours, some even longer (remember AF447?). Yes the flight is still "missing" despite some unconfirmed reports of wreckage sighting, but people need to think about this a little more logically than come to the conclusion "this is looking a lot like MH370".