Azerbaijan has observed a nationwide day of mourning for the victims of the plane crash that killed 38 people and left all 29 survivors injured.

Azerbaijan Airlines’ Embraer 190 was en route from Azerbaijan’s capital of Baku to the Russian city of Grozny on Wednesday when it was diverted for reasons that are yet unclear.

It crashed while attempting to land in Aktau, Kazakhstan after flying east across the Caspian Sea.

The Associated Press says national flags were lowered across Azerbaijan on Thursday, with traffic across the country stopped at noon and signals sounded from ships and trains as the country observed a nationwide moment of silence.

Speculation is mounting about a possible cause of the crash which currently remains unknown.