Questions were being asked Thursday about the cause of an airliner crash in Kazakhstan the day before, as Azerbaijan held a day of mourning for the dozens of victims of the disaster. The reasons that Azerbaijan Airlines flight J2-8243 came down are still unknown.

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,

An Azerbaijan Airlines Embraer 190 was en route from Azerbaijan's capital of Baku to the Russian city of Grozny when it crashed, killing 38 people onboard.