Aviation experts said Thursday that Russian air defense fire was likely responsible for the Azerbaijani plane crash the day before that killed

The Azerbaijan Airlines plane flew hundreds of miles off its scheduled route from Baku to Grozny, and crashed on the eastern shore of the Caspian Sea. Russia's aviation watchdog said a bird strike might have been the cause.

The Azerbaijan Airlines Embraer 190 flight left Baku, Azerbaijan, on Christmas to Grozny, Russia. Instead, the plane crashed in Aktau, Kazakhstan.

Increasing analysis suggests Russian air defenses might have downed Azerbaijan Airlines flight J2-8243, which crashed in a ball of fire near Aktau,Kazakhstan on Wednesday morning, killing 38 of 67 passengers and crew.

The flight was en route from the Azerbaijani capital of Baku to Grozny, in Russia’s south, when it diverted and attempted an emergency landing in Kazakhstan.

There was growing speculation that an Azerbaijani airliner was shot down by Russian air defense system. Russia had initially said it believed the plane hit a flock of birds, but a U.S. official says it may have been struck by Russian air defenses.

Aviation experts say that Russian air defense fire was likely responsible for the Azerbaijani plane crash that killed 38 people and left all 29 survivors injured.

The preliminary results of Azerbaijan’s investigation into the deadly crash of a civilian airliner point to the plane being hit by a Russian antiaircraft missile, or shrapnel from it, said people briefed on the probe.

The cause of a deadly plane crash in southwestern Kazakhstan is being investigated, and some officials are claiming Russian involvement.