"The plane landed and the crew told the controller that the landing was over," Igor Levitin told the Vesti news channel.
The Airbus A-310 then veered off the runway at Irkutsk airport and hit a concrete wall before bursting into flames.
Emergency services said that 120 people had been killed and 53 passengers who were rescued from the retail section were being treated in the hospital.
Prosecutors said they were considering a technical fault as one of the main versions in the crash.
Irkutsk, 5,000 kilometers (3,100 miles) east of Moscow, is the main airport for holidaymakers heading for Lake Baikal, a popular destination for Russians in the summer.
Levitin, who has been appointed the head of a government commission into the tragedy, said the runway was wet after rain, but an official from the Emergency Situations Ministry said the landing gear may have caught fire as the plane landed.
On May 3, an Armenian A-320 crashed in the Black Sea killing all 113 people on board.
In 2001, a Russian-made airliner crashed near Irkutsk with the loss of all 145 passengers and crew
