At least 15 people have been killed and 23 injured after a powerful blast rocked the Russian city of Volgograd, in what is a suspected suicide bombing.

The explosion on a trolleybus comes a day after a suicide bombing at the central station in the same city killing 17 people, which is believed to have been carried out by a female suicide bomber.

The blast took place near a busy market area in Dzerzhinsky district. The bus, seen here, is completely destroyed, the roof ripped off in the explosion, scattering debris all over the blast site.

Both incidents are being treated as an act of terror, though no group has claimed responsibility for the attacks.

Security has been beefed up at railway stations and airports across Russia, but the bombings have raised concern over the safety of the upcoming Winter Olympics, as Russia is set to host the event in February in the city of Sochi, west of Volgograd.

Written and presented by Alfred Joyner