A Russia-bound Azerbaijani airliner crashed in Kazakhstan on Wednesday after being diverted, killing 38 of the 67 people on board.
Here's what we know so far.
How did the plane crash happen?
Azerbaijan Airlines' Embraer 190 was flying from Azerbaijan's capital Baku to the Russian city of Grozny in the North Caucasus on Wednesday when it was diverted for reasons that are not entirely clear.
Crashed while attempting to land at Aktau, Kazakhstan, after flying east through the Caspian Sea.
At least thirty-eight people died when a Russia-bound Azerbaijan Airlines plane crashed in Kazakhstan on Christmas morning, a Kazakh official said, adding that 29 other people, including two children, survived the crash. Investigators are still working to determine the causes of the crash.
The plane crashed near the coast, about three kilometers from Aktau. Mobile phone footage circulating online shows the plane descending steeply before hitting the ground and exploding in a ball of fire.
Rescuers transported 29 people who survived the disaster to hospitals.
How did Azerbaijan react?
On Thursday, Azerbaijan celebrated a nationwide day of mourning. National flags were lowered across the country, traffic was suspended throughout the country at noon, and signals blared from ships and trains.
Speaking at a press conference on Wednesday, Azerbaijani President Ilham Aliyev said the weather forced the plane to change course from its planned course.
What do officials and experts say about the possible cause?
Authorities in Kazakhstan, Azerbaijan and Russia say they are investigating the crash. Embraer told The Associated Press in a statement that the company “stands ready to assist all appropriate authorities.”
The Russian civil aviation authority, Rosaviatia, said that preliminary information showed that the pilots headed to Aktau after a collision with a bird that caused an on-board failure.
Some commentators said that the holes visible in the rear of the plane after the crash probably indicate that it may have come under fire from Russian air defense systems while repelling an attack by Ukrainian drones.
Osprey Flight Solutions, a UK-based aviation security company, warned its clients that “an Azerbaijan Airlines flight was likely shot down by a Russian military air defense system.”
Osprey CEO Andrew Nicholson said the company issued more than 200 warnings during the war about drone strikes and air defense systems in Russia.
Asked on Thursday about claims that the plane was fired upon by air defense forces, Kremlin spokesman Dmitry Peskov told reporters that “it would be inappropriate to make hypotheses before investigators give a verdict.”
Authorities in Kazakhstan and Azerbaijan have similarly avoided commenting on the possible cause of the crash, saying it will be up to investigators to determine it.