Two hundred and twenty-four people were on board, most of them Russian. Officials say there are no survivors and the cause is still unknown. Over 150 bodies have been recovered so far, according Egypt's state-run information service. (Video via CNN)

The plane, operated by Russian airline Kogalymavia, was discovered in two separate pieces, and both black boxes were recovered.

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An Islamic State group affiliate based in the Sinai released a statement in multiple languages claiming responsibility, though they aren't known to have any weapons capable of shooting down an airplane flying at high altitudes.

Russian President Vladimir Putin has ordered an official investigation into the crash, and a criminal case has been opened against the airline.

And speaking at a military symposium, Egyptian President Abdel-Fattah el-Sissi welcomed Russian cooperation and said "the issue is being extensively investigated."

Sunday vigils were held across Russia as Putin declared a national day of mourning for the victims and their families.

This video includes images from Getty Images and Aktug Ates.