Speculation mounts over cause of Azerbaijan Airlines plane crash that left at least 38 dead

Azerbaijan held a day of mourning on Thursday for the dozens of victims of an airliner crash in Kazakhstan, as questions were being asked over the cause of the disaster.

​ Azerbaijan held a day of mourning on Thursday for the dozens of victims of an airliner crash in Kazakhstan, as questions were being asked over the cause of the disaster. Read More Breaking News, Latest News and Videos | CNN