The crash of an Azerbaijani airliner in Kazakhstan has killed 38 of 67 people on board. Azerbaijan Airlines’ Embraer 190 was en route from Azerbaijani capital Baku to the Russian city of Grozny in the North Caucasus on Wednesday when it was diverted for reasons that aren’t fully clear yet.

T hursday is an official day of mourning in Azerbaijan as an investigation is underway to determine what caused an airplane carrying 67 passengers to crash on Christmas Day in Kazakhstan, killing 38 and leaving at least 29 survivors. Video posted by CNN shows the plane crash-landing, exploding into a fireball and plumes of black smoke.

Azerbaijani President Ilham Aliyev said on Sunday that a passenger plane that crashed last week, killing 38 people, had been damaged by shooting from the ground in Russia, and he said some in Russia had lied about the cause of the disaster.

The extraction of flight data from the Brazilian-made Azerbaijan Airlines plane that crashed in Kazakhstan last month was completed at a lab run by Brazil's air force, according to a statement released by the entity on Monday.

The Brazilian Air Force Laboratory has sent data from the flight recorders of an Azerbaijan Airlines plane to Kazakh investigators. The plane crashed on December 25 near the city of Aktau, Radio Liberty reports.