Just one day after a suicide bombing killed at least 17 people at a railroad station in Volgograd, a second suicide bomber attacked a bus during Monday morning's rush hour in the same southern Russian city, leaving at least 14 people dead. The attacks come just six weeks before February's Olympic Games in Sochi.

"For the second day, we are dying. It's a nightmare," a woman at the scene of the second attack told Reuters. "What are we supposed to do, just walk now?"

Russian authorities said the same type of bomb was used in both attacks. "That confirms the investigators' version that the two terror attacks were linked," Vladimir Markin, a spokesman for Russia's main investigative agency, said in a statement. "[The bombs] could have been prepared in one place."

So far, no suspects have been named and no terror groups have claimed responsibility, though there's widespread speculation the attacks were the work of Chechen rebel leader Doku Umarov, who has claimed responsibility for suicide bombings in Moscow in 2010 and 2011 that left a combined 77 people dead. In a video released in July, Umarov described the Sochi Olympics as "satanic dances on the bones of our ancestors."

"We as mujahedeen are obliged to not permit it, using any methods allowed us by the almighty Allah," Umarov added.

After Monday's bombing, Russian President Vladimir Putin ordered increased security at Russia's airports and other transportation hubs, though Russian Olympic Committee chief Alexander Zhukov said there will be no changes to security in and around Sochi because "everything necessary has already been done." Based on the Associated Press' description of security at Sochi, Zhukov's statement seems accurate enough.

Anyone wanting to attend the games that open on Feb. 7 will have to buy a ticket online from the organizers and obtain a "spectator pass" for access. Doing so will require providing passport details and contacts that will allow the authorities to screen all visitors and check their identities upon arrival.

The security zone created around Sochi stretches approximately 100 kilometers (60 miles) along the Black Sea coast and up to 40 kilometers (25 miles) inland. Russian forces include special troops to patrol the forested mountains flanking the resort, drones to keep constant watch over Olympic facilities and speed boats to patrol the coast.

The security plan includes a ban on cars from outside the zone from a month before the games begin until a month after they end.

American law enforcement officials also expressed confidence in security at Sochi, though there is some concern about other cities in Russia. "There's every belief they'll make it secure and do whatever it takes to do that," said one senior law enforcement official told the New York Times. "But it is a large country, and these groups can get a lot of bang for their buck if they are able to do something in the country, wherever it is, during the Olympics."

[Image via AP]