Four people have been killed and 15 injured after a bus ploughed into an underpass in Moscow.

Multiple videos show the vehicle swerving off one of the Russian capital's busiest roads at speed at around 3pm local time (12pm GMT).

It collapses down a wide set of steps leading to a subway before being stopped by the tunnel's roof, as panicked passers-by scatter.

Passengers on-board and people walking on the steps near the Slavyansky Boulevard metro station were killed.

Moscow police are looking into two possible causes - the driver losing control and a technical problem with the vehicle.

"The driver of the bus began movement and then changed his trajectory, which resulted in the bus going down into the pedestrian underpass," they said.

Source: SkyNews