Experts say that the Volgograd bombings may bode ill for security at the Sochi Games, which begin on February 7.
The girls, former students from Moscow and Volgograd universities, preferred to keep their real Russian names anonymous.
And some say that recently they were joined by “Night Wolves,” a biker gang from Volgograd.
Four things you need to know about the twin suicide bombings that hit Volgograd ahead of the Sochi Olympics.
Note: The city is a major commercial and industrial center.
Note: From 1925 to 1961, it was named Stalingrad. During the brutal winter of 1942–1943, a huge German invasion force besieged the city but ultimately failed to take it. The German defeat in the Battle of Stalingrad was a major turning point in World War II, marking the beginning of the end for the Nazis.