There are early indications that a Russian anti-aircraft system may have struck the Azerbaijan Airlines plane that crashed in Kazakhstan, killing dozens, a U.S. official told ABC News. If these indications prove true,

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.

Moscow on Thursday warned against speculation that Russian air defenses may have caused the crash of an Azerbaijan Airlines plane in Kazakhstan this week that killed 38 people. Kremlin spokesperson Dmitry Peskov told reporters that it was “necessary to wait for the end of this probe” before casting any speculation.