The LifeNews website published a photograph of the crash, showing the wreckage of the green bus and the Kamaz truck, which had been carrying a load of bricks.
The Tass news agency, citing a police spokeswoman, said the driver of the bus appeared to have crossed into oncoming traffic on a busy highway near the Siberian city of Omsk. The investigation was ongoing.
The bus was carrying workers from a local poultry factory, police spokeswoman Larisa Tsygal said.