The Kremlin on Thursday warned against speculating about what may have caused an Azerbaijan Airlines flight to crash, killing 38 of the 67 people on board, after an aviation expert said evidence indicated that a Russian anti-missile battery may have brought down the passenger plane.

The Embraer 190 crashed Wednesday near the Kazakh city of Aktau while en route from Baku, the capital of Azerbaijan, to Grozny, the capital of Chechnya, Russia. The flight attempted to make an emergency landing about 1.8 miles from Aktau, according to Azerbaijan Airlines, but instead hit the ground, erupted into a fiery ball and split in two.

President Vladimir Putin’s spokesperson Dmitry Peskov said the investigation into the cause of the crash was underway.

“It would be incorrect to make any hypotheses before the investigation comes to conclusions, and we definitely cannot do it and no one should do it,” he said in his daily news conference.

Putin's and Bozumbayev's comments come amid growing speculation that Russian air defenses may be behind the crash.

"Subsequent reporting and contextual information, including the follow-on video examination of the wreckage ... and circumstances surrounding the airspace security environment in southwest Russia, leads Osprey to assess that the flight was likely shot down by a Russian air defense system," said Matthew Borie, chief intelligence officer at the aviation security firm Osprey Flight Solutions.

Borie said another potential theory, that the plane collided with a bird or birds, would have probably led to reports of more than one explosion and the damage to the aircraft appearing differently.

The Wall Street Journal first reported Osprey's findings.

A U.S. official on Thursday echoed that there are indications a Russian anti-aircraft system may have struck the Azerbaijan Airlines flight, and said if that proves to be the case, it would be more evidence of Russia's recklessness in its war with Ukraine.

Borie said that, at the time of the incident, Russian air defense forces were defending against a Ukrainian military-grade weaponized drone attack that involved Russia shooting down drones. At least one drone was hit east of Grozny, while others were shot down over Chechnya, he added.

Earlier, the head of Ukraine’s Center for Countering Disinformation, Andriy Kovalenko, said that the Azerbaijan Airlines plane “was shot down by a Russian air-defense system,” citing visible damage to the plane.

The flight's destination was Grozny, which is near Ukraine and the ongoing war with Russia, but it was rerouted to Aktau after an emergency onboard, according to a statement issued by Russia’s aviation authority, Rosaviatsia, on Wednesday.

Azerbaijani President Ilham Aliyev echoed Peskov's caution. "There are various theories, but I believe it is premature to discuss them. The matter must be thoroughly investigated,” he said at a meeting dedicated to the incident Wednesday.

“The reasons for the crash are not yet known,” he said, adding that Azerbaijan has launched its own investigation.

Aliyev said that the flight changed course because of “worsening weather conditions” and that the “crash occurred during landing” as the plane descended toward Aktau airport.

He declared Thursday a national day of mourning in Azerbaijan.

The flight had 62 passengers and five crew members on board, according to the Kazakh Emergencies Ministry. Later, the Kazakh Health Ministry published a list of 29 survivors, including two children.

At least one airline said it is altering its flights in the region in light of the Kazakhstan air crash. El Al, Israel's national carrier, announced Thursday it is suspending its operations on its Tel Aviv-Moscow route for the coming week and will assess when they may resume.