At least 14 killed after second explosion in Volgograd
At least 14 people have been killed in a suicide bombing on a trolleybus in the Russian city of Volgograd, investigators say.
The blast comes a day after 17 people died in another suicide attack at the central station in the city.
Security has been tightened at railway stations and airports across Russia.
The bombings have fuelled security concerns ahead of February's Winter Olympics in Sochi.
Daniel Sandford reports.
30 Dec 2013