Russian investigators are trying to determine why the crew of a plane that crashed at an airport were unable to land on the first attempt.
Alexander Poltinin, the head of the local branch of Russia's Investigative Committee, said they are looking at the possibility of pilot error or equipment failure.
The traffic controller at Kazan airport said the crew told him they were not ready for landing as it was approaching, but did not specify the problem.
One of the plane's two black boxes has been found, Mr Poltinin said, adding it could take weeks to identify some of the victims.
More top news
Ukip remains the party most trusted to control immigration despite more people seeing them as racist, a ComRes/ITV News poll has found.
Some say it's white and gold and others claim it's blue and black. So why do we see things differently?
New figures show that heart disease and dementia are the leading cause of deaths for people in England and Wales in 2013.