Russian President Vladimir Putin on Monday instructed the National Anti-Terrorism Committee to increase security around the country after two suicide bombers attacked Volgograd, killing more than 30 people.
Officials say the most recent blast, which occurred Monday morning, killed 14 on board a trolleybus, according to multiple reports. Less than 24 hours earlier, a bomber struck a train station in the city, leaving 17 dead. The attacks come about five weeks before the Winter Olympics are scheduled to take place in the region.
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Volgograd, formerly known as Stalingrad, is a city of about 1 million people. It's located 430 miles northeast of Sochi, where the upcoming Olympic games scheduled to take place. Sochi is also one of 11 Russian cities scheduled to host the 2018 World Cup.

Authorities say they believe the two attacks are linked because the explosive devices used were similar.
"That confirms the investigators' version that the two terror attacks were linked," Russian Investigative Committee spokesman Vladimir Markin said in a statement, the AP reports. "They could have been prepared in one place."
Volgograd and Sochi lie near the tumultuous North Caucasus region, a group of provinces that includes Chechnya and Dagestan. Chechnya has intermittently resisted Russian rule for the past two centuries. Most recently, Russia has been involved in two wars with Chechnya in the past two decades, initially losing control of the province in 1996 but reestablishing its rule in 2000.
Russia has committed tens of thousands of police officers to protect the Sochi games, pledging to host "the safest Olympics in history."
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