An intercity bus has veered off a road in western Russia killing four people and injuring another 11, authorities said.

The bus, driving from Moscow to Volgograd, swerved into a ditch and overturned in the Ryazan region, about 155 miles south of Moscow.

Four people including the driver died and at least 11, including several children, were taken to hospital with injuries after the overnight crash, authorities said.

Police said the driver may have lost control of the bus after falling asleep.