Dec. 29, 2013 -- A suicide bombing has killed at least 15 people and injured over 40 in the southern Russian city of Volgograd, raising concerns about terrorism just over a month before Russia hosts the 2014 Winter Olympic Games.
A female bomber carried out the blast in a Volgograd train station, 400 miles from the site of the upcoming Olympics in the Russian resort town of Sochi, Russian authorities said. The Sochi 2014 Olympic Games are scheduled to begin on Feb. 7.
A total of 33 people were hospitalized, with eight in serious condition and one in "extremely serious condition," Oleg Solagai, a spokesman for the Russian health ministry, told Russian news agency Rossiya24.
Authorities in Volgograd said the attack left 27 people seriously injured, and that the death toll may increase. A police officer was among the dead, and a nine-year-old girl was injured, authorities said.
A severed head found at the site of the bombing is suspected to be that of the woman who carried out the attack, making it "possible to identify her," a Volgograd law enforcement source told the Russian news agency Interfax. Investigators have reason to believe the woman came from Russia's Dagestan region, the source told the agency.
Azamat Suleymanov, an officer at the Interior Ministry of Dagestan, said they are fairly certain of the identity of the bomber.
"For legal reasons we cannot yet say that we are 100 percent sure, but we are almost confident that it was Oksana Aslanova, a Dagestani citizen," he said. "We have her on file. She was a widow whose husband died in a special operation conducted by our forces. She was then married a few times more, always to terrorists."
The bombing took place in the same city where another female suicide bomber was blamed for an attack an October bus attack that killed seven people, including the bomber.
The train station attacked today is one of the five largest in Russia and is a major transit point for much of southern Russia. It was unclear whether the train station was the woman's intended target or whether she planned to travel elsewhere to carry out an attack.
Like the October bomb attack, today's blast was caught on camera. Surveillance video showed the exact moment the explosion took place, just inside an entranceway to the train station.
Volgograd reeled from the attack just before the New Year's celebrations, a major holiday in Russia that would have likely meant a high amount of traffic was passing through the train station today.
Yulia Chemova with Volunteers of Russia, who was at the railway station minutes after the attack to help out, told ABC News she believed the attack was planned around the New Year holiday.
"The timing for the terrorist attack in Volgograd is perfect," she said. "It's holiday season; airports and train stations are packed at this time of year."
There have been 32 terrorist attacks in Russia in the year ahead of Sochi 2014, according to Kavkazskiyuzel, a Russian think tank.
The power of today's explosion was equivalent to at least 22 pounds of TNT, and police officers averted a much larger tragedy by stopping the woman right at the entrance to the train station, according to a committee investigating the attack. Had she made it inside, a spokesman for the committee said, casualties could have reached the hundreds.
Russian state TV named the policeman who died in the attack, and allegedly saved many lives by stopping the bomber before she entered the main hall of the station, as 29-year-old sergeant Dimitry Makovkin.
Russia's interior ministry said it would deploy more police at all rail stations in Russia and that passengers would be subject to strict security measures.
Today's attack bore some similarities to the October bus bombing, which authorities said was also carried out by a woman from Dagestan. Russia has for years been fighting an Islamist insurgency in the North Caucasus, a region that encompasses the restive Russian regions of Chechnya and Dagestan, as well as the Olympic host city, Sochi.
Suicide bombers, often female, from Chechnya or Dagestan and sometimes known as "black widows," have carried out many attacks on Russian targets in the past decade, including the dual bombing of the Moscow subway in 2010 that claimed 39 lives. Female bombers from the Caucasus were also blamed for the simultaneous bombing of two Russian airplanes in 2004, an attack that killed 90 people.
Tomek Rolski, Dragana Jovanovic, Max Karmen, Muhammad Lila and Tanya Stukalova contributed to this article.