An Azerbaijan Airlines jet carrying 67 people crashed in the Kazakh city of Aktau, killing at least 38 of those on board, after veering from its scheduled route.
Kazakh authorities said 29 people survived the crash of the Embraer 190 near the city of Aktau on Wednesday, an oil and gas hub on the eastern shore of the Caspian Sea.
The plane was flying from the Azerbaijani capital Baku on the western shore of the Caspian to the city of Grozny in Chechnya in southern Russia.
The plane's course on Flight Radar showed it crossing the Caspian Sea away from its normal route and then circling over the area where it eventually crashed.
The ministry confirmed in a Telegram statement on Wednesday, that 67 people, including five crew, were on board the plane.
Azerbaijan Airlines, the country's flag carrier, said the jet had "made an emergency landing" about 3 kilometres from Aktau, an oil and gas hub on the eastern shore of the Caspian Sea on Wednesday, local time.
Russian news agencies said the plane had been rerouted due to fog in Grozny.
An eyewitness video verified by Reuters shows passengers wearing oxygen masks in the cabin before the plane crashed.
The Kazakh transport ministry said that of the plane's passengers 37 were from Azerbaijan, six from Kazakhstan, three from Kyrgyzstan and 16 from Russia.
The Kazakh emergency situations ministry said its staff put out a fire which broke out when the plane crashed.
It said 150 emergency workers were at the scene.
Authorities in Kazakhstan said they had begun looking into different possible versions of what had happened, including a technical problem, Russia's Interfax news agency reported.
Russia's aviation watchdog said the crash came shortly after an on-board emergency which may have been caused by a "collision with birds".
The office of Azerbaijan's prosecutor general said "all possible scenarios are being examined" while investigating the reasons for the crash.
"An investigative team, led by the deputy prosecutor general of Azerbaijan, has been dispatched to Kazakhstan and is working at the crash site."
Azerbaijani President Ilham Aliyev's office said he cut short a visit to Russia in light of the crash and ordered "the prompt initiation of urgent measures to investigate the causes of the disaster".
"I extend my condolences to the families of those who lost their lives in the crash … and wish a speedy recovery to the injured," Mr Aliyev said in a social media post.
Russian President Vladimir Putin expressed his condolences to Mr Aliyev over the loss of life in the plane crash, Kremlin spokesman Dmitry Peskov said.