"Presumably a gas canister blast occurred in the dining car of Train 33 en route from Vladikavkaz to Moscow near the village of Persiyanovka [in southern Russia's Rostov Region] at 08:30 a.m. Moscow time (05:30 GMT)," the spokesman said.

Two of the injured are reported to be in serious condition.

The explosion started a fire in the car, but it was soon extinguished. Investigators and police are currently on the way to the scene.