Kremlin spokesman Dmitry Peskov said on Thursday that it would be wrong to speculate about the cause of the plane crash before an investigation had been carried out, according to Russian state media RIA Novosti.

Maulen Ashimbayev, chairman of Kazakhstan’s senate, said Thursday that “the nature of these damages and the causes of the disaster are currently unknown.”

A commission has been set up to investigate the crash, involving representatives from Kazakhstan, Azerbaijan and Russia, Ashimbayev said.

Kanat Bozumbayev, Kazakhstan’s deputy prime minister, said that “even the preliminary cause cannot be determined yet, as specialists are needed for that.”

“They will conduct the work, and then it will be clear,” Bozumbayev said Thursday.

CNN’s Darya Tarasova contributed to this report.

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