Experts say evidence in the Azerbaijan Airlines plane crash in Kazakhstan points to a possible midair explosion, not an encounter with a flock of birds.

The Embraer 190 was traveling to Grozny, Russia, but crashed near Aktau, Kazakhstan, killing 38 people onboard. Investigators are focusing on Russian air defense as the likely cause.

After an Azerbaijan Airlines jet crashed in Kazakhstan, speculation mounted about why the plane went down and whether possible Russian air defense action may have played a role.