Azerbaijan on Thursday observed a nationwide day of mourning for the victims of the plane crash that killed 38 people and left all 29 survivors injured as speculation mounted about a possible cause of the disaster, with some experts saying that the airliner was damaged by Russian air defense fire. Azerbaijan Airlines’ Embraer 190 was en route from Azerbaijan’s capital of Baku to the Russian city of Grozny in the North Caucasus on Wednesday when it was diverted for reasons yet unclear and crashed while making an attempt to land in Aktau in Kazakhstan after flying east across the Caspian Sea. The plane went down about around 2 miles from Aktau.