According to him, an accident involving a passenger bus occurred on the M5 Ural highway in the Syzran region.
"As a result, 11 people were killed, 13 injured," the governor wrote.
He said that he keeps the situation under personal control.
Azarov added that he had interrupted a business trip in Moscow and was leaving for the region.
Earlier it was reported about ten dead and 14 injured.
The UK considers the maneuver of the bus as a preliminary cause of the accident.
A criminal case was initiated.