ASTANA, Kazakhstan (AFP) — Azerbaijani and United States (US) officials believe a Russian surface-to-air missile caused the deadly crash of an Azerbaijani passenger jet, media reports and a US official said Thursday, as the Kremlin cautioned against “hypotheses” over the disaster.

The Azerbaijan Airlines jet crashed near the Kazakh city of Aktau, an oil and gas hub, on Wednesday after going off course for undetermined reasons.

Thirty-eight of the 67 people on board died.

The Embraer 190 aircraft was supposed to fly northwest from the Azerbaijani capital Baku to the city of Grozny in Chechnya, southern Russia, but instead diverted far off course across the Caspian Sea.

An investigation is underway, with pro-government Azerbaijani website Caliber citing unnamed officials as saying they believed a Russian missile fired from a Pantsir-S air defense system downed the plane.

The claim was also reported by The New York Times, broadcaster Euronews and the Turkish news agency Anadolu.

Some aviation and military experts said the plane might have been accidentally shot by Russian air defense systems because it was flying in an area where Ukrainian drone activity had been reported.

A former expert at France’s BEA air accident investigation agency said there appeared to be “a lot of shrapnel” damage on the wreckage.

Speaking on condition of anonymity, he said the damage was “reminiscent” of Malaysia Airlines flight MH17, which was downed with a surface-to-air missile by Russia-backed rebels over eastern Ukraine in 2014.