Definitely a stall loss of control event - many possibilities that the investigators will look at. Weight and balance might be interesting - doubt they would be much below maximum landing weight with a full load of pax and no doubt lots of cargo/climbing equipment etc…
To me it looks like they had quite a groundspeed going on before the left turn. Maybe some strong low level valley winds leading to a windshear event coupled with high density altitude. Aerodynamics and engines much less able under such conditions. Or a nasty little inversion - quite a noticeable line of smog that might offer a clue to this sneaky little windshear clue. So perhaps not as much margin for the crew to play with as some may think.