Kazakhstan's transport minister said Russian authorities told them that an oxygen cylinder had exploded in the passenger cabin of the aircraft.

The flight was en route from the Azerbaijani capital of Baku to Grozny, in Russia’s south, when it diverted and attempted an emergency landing in Kazakhstan.

Mobile phone footage circulating online appeared to show the aircraft making a steep descent before smashing into the ground in a fireball. Some of the videos posted on social media showed survivors dragging fellow passengers away from the wreckage.