At least 14 people were killed Monday when a suicide bomber set off a blast aboard a packed commuter bus around 8:10 a.m. local time. In addition to the dead, 28 were injured by the blast. Investigative Committee spokesman Vladimir Markin believes Monday's bus attack is linked to Sunday's suicide bombing at the Volgograd-1 railway station.
Monday's deadly bus attack comes a day after a female suicide bomber detonated herself on at the city's central train station around 12:45 p.m., killing seventeen people.
No one has yet claimed responsibility for the bombings.
The attacks occurred as Russians are preparing for the New Year's holiday and as the country prepares to host the February Winter Olympics in Sochi, 400 miles from Volgograd. Russian President Vladimir Putin promised Sunday to increase security at Russian railways and airports.
Volgograd is 560 miles south of Moscow.