She added that 28 passengers are now in the airport terminal, and five have been taken to a hospital.
A group of experts trained in providing psychological assistance to survivors and relatives of victims has been sent to the airport.
President Putin has offered his condolences over the incident.
Kremlin press secretary Dmitry Peskov said Putin has ordered "the most thorough investigation" to find out the cause of the disaster.
According to Russia's ITAR-Tass News Agency, a criminal case was opened after the incident on charges of violating flight safety rules.
Markovskaya said a commission headed by Russian Transport Minister Yevgeny Dietrich is working at Sheremetyevo.
Authorities in the Murmansk region have declared a three-day period of mourning. Andrei Chibis, the region's acting governor, announced the mourning period on Facebook.
