Earlier today, a bomb exploded on a trolley bus in the Russian city of Volgograd, leaving 14 people dead and 28 injured. It marked the city's second bombing since yesterday and the country's third since Friday.

According to NBC News, authorities say a suicide bomber was responsible for the blast, amplifying fear about potential attacks in the wake of the Sochi Winter Olympics, which will be held in Russia in just over a month. The second attack took place yesterday, when another suspected suicide bomber killed 17 people at the Volgograd train station.

Vladimir Markin, a spokesman for Russia's primary investigative agency, says today and yesterday's bombings were probably related because the bombs were "identical." The first incident—a car bombing which took place on Fridaykilled three people in the city of Pyatigorsk, which is a mere 170 miles from where the Olympic games will be held. 

[via NBC News]