Two deadly bombings have struck the southern Russian city of Volgograd in the past two days, leaving at least 31 people dead and as many as 70 wounded in what appear to be suicide attacks. Although Volgograd is hundreds of miles away from the site of the February Olympics in Sochi, the violence has raised concerns about terrorism at the Games. Sunday's explosion took place at the main train station. Today's blast destroyed a trolley during the morning rush hour. Will England is Moscow correspondent for the Washington Post.