Video: Explosion at Volgograd station

Footage captures the moment a suspected suicide bomber struck the central station of the southern Russian city Volgograd (YouTube)

CCTV footage has captured the moment a bomb exploded in Volgograd station in Southern Russia.

The video shows the station being lit up by the bomb as it goes off, sending plumes of smoke out of the front of the building.

The attack is the first of two, there was a second explosion today on a bus in Volgograd which has left 14 people dead.

The morning rush hour blast, which federal investigators have called a "terrorist act", reduced the trolleybus to a twisted, gutted carcass, its roof blown off and bodies and debris strewn across the street.

Russian investigators said they believe the explosion was caused by a male suicide bomber who detonated the bomb in the vehicle's passenger area.

"It is now possible to preliminarily say that the explosive device was set off by a suicide bomber - a man whose body fragments have been collected and sent for genetic testing," the federal Investigative Committee said in a statement.

The two explosions in close concession have put the city on edge and highlighted the terrorist threat that Russia faces, as it prepares to host the Winter Olympics in February.