CCTV footage from the scene shows a bus veering off the road and smashing down the steps in a busy part of Moscow.
At least five people were killed and 15 injured after a bus ploughed down the stairs into a Moscow Metro station on December 25, RT reported.
The reason as to why or how the bus - used for public transport - came off the road is still being investigated by detectives.
It is not clear what caused the crash but Russian media said the driver had been detained after he lost control of the vehicle.
Either the vehicle's brakes failed or a auto cut ahead of the bus, causing it to veer off its intended path.
Russian emergency services released a video from the incident site showing the bus wreckage and ambulances.
A preliminary examination showed the driver of the bus was sober, news agencies said.
Several people were killed and more than a dozen injured when a bus drove into an underground passageway in Moscow.
Investigators are now looking into whether the smash was down to driving error or a fault with the bus.
Monday was an ordinary working day in Moscow.
A number of people taken to hospital are said to be in a life-threatening condition.
Moscow mayor Sergei Sobyanin tweeted: "There are dead and wounded".