Russian President Vladimir Putin on Saturday apologized to his Azerbaijani counterpart for what he called a “tragic incident” following the crash of an Azerbaijani airliner in Kazakhstan that killed 38 people.

The plane was flying on Wednesday from Azerbaijan’s capital of Baku to Grozny, the regional capital of the Russian republic of Chechnya, when it turned toward Kazakhstan and crashed while making an attempt to land.

There were 29 survivors.

In an official statement Saturday, the Kremlin said air defense systems were firing near Grozny on Wednesday due to a Ukrainian drone strike, but stopped short of saying one of these hit the plane.

On Friday, a U.S. official and an Azerbaijani minister made separate statements blaming the crash on an external weapon.