The crash of a passenger jet heading from Azerbaijan to the Chechnya region of Russia on Christmas Day has killed at least 38 people, officials said.

Azerbaijan Airlines flight J2-8243 flew “hundreds of miles off its scheduled route” before going down near the Kazakh city of Aktau, on the opposite shore of the Caspian Sea, Reuters reported

Video footage captured by a witness on the ground shows the plane failing to land safely, bursting into flames and breaking into pieces upon impact:

It is unclear why the flight diverted so far from its path, though Russia’s aviation watchdog said it may have been an emergency caused by a bird strike. Azerbaijan President Ilham Aliyev said there was bad weather, and Reuters noted that drone activity in the south of Russia had shut down airports in the area. 

The plane, an Embraer 190 jet, was flying from the Azerbaijani capital of Baku to Grozny, the capital of the Chechen Republic in southern Russia.

The aircraft was carrying 67 people, with 29 survivors receiving medical treatment, Kazakh officials told NPR.

They added that the passengers included 42 Azerbaijani citizens, 16 Russian nationals, six Kazakhs, and three Kyrgyzstan nationals.

“This is a great tragedy that has become a tremendous sorrow for the Azerbaijani people,” President Aliyev said in a statement. 

“The information provided to me is that the plane changed its course between Baku and Grozny due to worsening weather conditions and headed to Aktau airport, where it crashed upon landing,” the Azerbaijani leader added.

He also declared that December 26 would be a national day of mourning.

Russian President Vladimir Putin has already called Aliyev to share his condolences, according to Kremlin spokesman Dmitry Peskov.

Speaking at the Commonwealth of Independent States (CIS) – a Eurasian intergovernmental organization — meeting in St. Petersburg, Putin also said his country sent an Emergency Ministry plane to aid victims and assist local authorities after the devastating crash. 

Kazakhstan, Azerbaijan, and Russia all said they would be investigating the tragedy, and plane manufacturer Embraer told the Associated Press in a statement that the company is “ready to assist all relevant authorities.