A Boeing 737 operated by a Russian airline crashed on Sunday while attempting to land in the city of Kazan, killing all 50 on board, Russia's emergency situations ministry said.
"According to preliminary information, all the people on board the flight, 44 passengers and six crew members, were killed," a ministry spokeswoman told AFP.
"The Boeing 737 that flew out of Moscow's Domodedovo airport with 44 passengers crashed onto the runway at Kazan airport on landing and burst into flames," Russia's Investigative Committee, which probes serious incidents, said in a statement.
The emergency situations ministry posted photographs of fragments of the plane scattered across the runway of the airport in Kazan, which is around 720 kilometres (450 miles) east of Moscow.
The plane, owned by Tatarstan Airlines, was making a second attempt to land, the spokesman for Russia's civil aviation authority, Sergei Izvolsky, told the Interfax news agency.
"We know for sure that when the plane tried to make a second landing, for some reason, the plane hit the surface of the runway near the air traffic control tower, as a result of which the plane crashed and burnt."
The plane's black boxes have not yet been found, Izvolsky said.
Russian President Vladimir Putin expressed his "deep condolences to the relatives and loved ones of those who died in the plane crash at Kazan airport," the Kremlin said in a statement.
"After receiving a report on the air crash, the head of state ordered the government to urgently form a commission to investigate the reasons and circumstances of what happened."
The emergency ministry published a list of the names of 44 victims, while saying that six were still being identified. The airline named the chief pilot as 47-year-old Rustem Salikhov.
Among the dead was the 24-year-old son of the leader of the Tatarstan region where Kazan is located, Irek Minnikhanov, the RIA Novosti news agency reported, citing the region's deputy prime minister.
The airline named an 11-year-old girl, Darya Artashina, as among those on the flight.
The head of the region's FSB security service, General-Lieutenant Alexander Antonov, also died in the crash, a member of the disaster management team told RIA Novosti.
Emergency landing last year
The Investigative Committee said an inquiry had been opened to determine whether there had been any "violation of aviation security rules" and added that several inspectors had been sent to the scene of the crash.
"Investigators are looking at different versions of what happened including a technical problem, pilot error and unfavourable weather conditions," it said.
"According to preliminary information all 50 bodies of the victims were found at the scene of the crash," said an official at the local emergency medical centre.
The plane, which had been flying since 1990, had last year made an emergency landing at the same airport, Russian television reported.
Its owner, the Tatarstan Airlines, in a brief statement on its website said that "the circumstances are being clarified."
The airline, founded in 2000, has a fleet of eight planes, including two Boeing-737s.
The Life News website reported that the plane had originally been flown by Air France before being operated by airlines in Uganda, Brazil, Romania and Bulgaria.
Tatarstan Airlines bought the plane in 2008, Life News reported.
Air safety in Russia is a major issue for the authorities following a severe deterioration in the quality of domestic services after the collapse of the Soviet Union.
Officials blame most problems on pilot inexperience as well as poor maintenance by the small and poorly regulated airlines that have sprung up across Russia in the past two decades.
Kazan is the capital city of the Russian republic of Tatarstan, which has a large Muslim population and is seen as an example of peaceful integration of different ethnic groups.
VIDEO: 50 dead as Boeing 737 crash lands in Kazan, Russia