A second deadly bomb attack in less than 24 hours hit the Russian city of Volgograd on Monday killing 14 people and wounding nearly 30 others.

A powerful blast tore through a trolleybus shortly after 8 a.m. during the morning rush hour. Video footage and pictures posted online showed the trolleybus, which can carry up to 80 people, literally ripped apart, its roof blown out and bodies strewn on the road.

Security officials said the blast, equivalent to 4 kg of TNT, could be linked with a terror attack staged by a suicide bomber 19 hours earlier at the main railway station of Volgograd. Sunday’s attack killed 17 people and wounded more than 40.

“According to preliminary information, the bomb in the trolleybus was set off by a male suicide bomber,” said Vladimir Markin, spokesman for Russia’s Investigation Committee. “Both bombs were filled with identical shrapnel and were probably made by the same terrorist group.”

The railway station blast also seems to have been staged by a male suicide bomber. Based on preliminary information, security service sources on Monday identified him as an ethnic Russian male named Pavel Pechenkin, a paramedic from the autonomous republic of Mari El, who in 2012 ago had joined radical Islamists in the North Caucasus.

Russia’s Health Minister Veronika Skvortsova said 14 people were killed and 41 were injured in the trolleybus blast. She did not rule out that the death toll could rise as some of those injured were in extremely grave condition.

The consecutive bomb attacks in Volgograd appeared to have been carefully planned.

“The terrorists must have factored in that the city railway station was packed on Sunday as dense fog had shut down air traffic in Volgograd,” said Alexei Volotskov, deputy in the local legislature. “Similarly, the bombed trolleybus on Monday was crowded with people heading to a big market in the area to stock up for New Year celebrations.”

Experts said the terrorists singled out Volgograd because it was a large city with a population of one million and a major transport hub for southern Russia, with many links to the North Caucasus, where Russian security forces are still battling Islamist insurgency. Also, Volgograd, former Stalingrad, was an attractive target for terrorists as a symbol of Russia’s victory in World War Two.

Two months ago a female bomber blew herself in a bus in Volgograd, killing seven people.

The latest blasts in Volgograd are the worst in Russia since a suicide bomber killed 37 people at Moscow’s Domodedovo airport in January 2011.

The surge in terror attacks comes a little over month ahead of Winter Olympic Games in Sochi in Russia’s troubled North Caucasus, which is just over an hour’s flight from Volgograd.

Nobody has so far claimed responsibility for the latest attacks but many earlier strikes were owned by Chechen warlord Doku Umarov, the self-proclaimed leader of the “Caucasus Emirate.”

In a video posted on the web in July Umarov urged militants to use “maximum efforts” to wreck the Olympics, denouncing the games as “Satanist dances on the bones of our ancestors.” He said he was lifting a moratorium on attacks against civilian targets outside the North Caucasus that he had declared almost two years ago.

Russian President Vladimir Putin has promised to ensure “absolute security” of the Sochi Olympics.

After the second blast in Volgograd Mr Putin instructed the National Anti-Terror Committee to step up security across Russia, but neither he, nor Prime Minister Dmitry Medvedev has made any statement on the new terror attacks.

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