The latest blast, during rush hour Monday morning, killed 14 people, CNN reported. The explosion appeared to have happened in the back of a trolley bus and was set off by a male suicide bomber.
USA Today reported Sunday that 16 people were killed in the first blast at a Volgograd train station. It fit a pattern of previous terror attacks in the country.
Volgograd, known as Stalingrad during the Soviet Union era, is one of the country’s main railway hubs. It is 620 miles away from Sochi, where the Winter Olympics is scheduled to take place Feb. 7 through Feb. 24.
Chechen rebel leader Doku Umarov called for terrorist attacks at the Sochi Olympics and other civilian targets earlier. Umarov said that he wanted Chechen separatist groups to work together to prevent the Olympics from happening.
“An open question is how much authority (Umarov) really has over these different groups,” Jeffrey Mankoff, deputy director at the Center for Strategic and International Studies’ Russia and Eurasia Program told USA Today. “A lot of the attacks seem to be inspired by Umarov but may not be directly controlled by him.”