The deadly attack came on Monday, a day after a suicide bomber killed at least 17 people in the main railway station just 40 days before the Russian Winter Olympics is to be held in the Black Sea resort of Sochi.
According to federal investigators, the blast is believed to be a “terrorist act.” State TV channels showed twisted, gutted remains of the blue-and-white trolleybus explosion, its roof blown off and debris strewn around the street, reports Reuters.
The attacks being consecutive have underscored Russia’s vulnerability to militants, which will raise fears of a concentrated campaign of violence prior to the Russian Olympics that is to begin on February 7 in Sochi, situated 430 miles southwest of Volgograd.
The Olympics games to be held at Sochi are a major prestige project for President Vladimir Putin. Insurgents who want to have an Islamic state out of southern Russia posted a Web video in July urging militants to use “maximum force” to prevent the Olympics from taking place.
No one has yet claimed responsibility for either of the attacks, which has left dozens wounded in addition to the deaths. After the first attack that took place on Sunday, authorities have said that 37 people were hospitalized and 23 have been reported wounded on Monday.