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.

The second black box has been found at the plane crash site near Aktau and handed over to the investigation department, according to a Kazakh official from transport department on Thursday. The Embraer 190 aircraft operated by Azerbaijan Airlines flight J2-8243 from Baku to Grozny crashed near Aktau Airport in Kazakhstan on Wednesday.

The Azerbaijan Airlines flight from Baku to Grozny in Russia was carrying 67 people when it crashed near Aktau early Wednesday. Kazakh officials said 29 people survived.