"Six people suffered when [seven oil] cisterns were derailed, damaging a car, bus, and a MAZ truck," the railroad monopoly said. "The driver of the VAZ traffic police car was killed, its passenger, the bus driver and two passengers, and the truck driver were injured."
Three victims were hospitalized.
The accident took place at a railroad crossing in the central region of Samara at 9.18 a.m. (5.18 a.m. GMT) Sunday.
"Preliminary reports say the collision was caused by the bus driver, who did not apply brakes in due time and pushed the traffic police car into the moving freight train," the company said, adding that the traffic lights had been in order.
Seven cistern cars were derailed when the automobile ran into them. Four oil cisterns caught fire, the company said.
The company said the fire had been extinguished now and the train towed away. Traffic was partly reopened by 3 p.m. Moscow time (11 a.m. GMT).
The company said oil would not spill into local water supply sources or subsoil water.
Some 1,000m of railroad track were damaged, but are being repaired already, according to the company.
