MOSCOW (CNN) -- A massive explosion at a train station in the Russian city of Volgograd killed at least 14 people, including one police officer, the Investigative Committee of Russia said on its website Sunday.
The head of the committee, Vladimir Markin, said 14 people had been killed and 34 people were injured, including a 9-year-old girl.
The female suicide bomber set off the device before she could pass through a metal detector, Markin said, citing available information.
He said the bomber used the equivalent of 10 kilograms of TNT and included shrapnel.
Video taken from an outside security camera shows a huge fireball inside what appears to be the main entrance followed by a steady trail of smoke coming out shattered windows.
The bombing occurred at about 12:45 p.m. local time (3:45 a.m. ET), officials said.
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Prime Minister Dmitry Medvedev has expressed his heartfelt condolences to the families of the Volgograd bombing victims, the Russian government said on Twitter.
He ordered the emergency and health ministry to provide "all necessary assistance" to the wounded.
It is the second bombing in the southern Russian city in two months and comes less than six weeks ahead of the Winter Olympics in Sochi, located less than 1,000 kilometers (620 miles) from Volgograd.
No one has claimed responsibility for the attack.
"There can be no justification for such barbarous attacks." said NATO Secretary General Anders Fogh Rasmussen. "NATO and Russia stand together in the fight against terrorism., including by working together on technology to prevent attacks on public transport systems."
In October, a bomber blew up a passenger bus, killing six people and wounding more than 30 others. Russian media reported that a female Islamist suicide bomber from the Russian region of Dagestan was responsible for the attack.
Volgograd, once called Stalingrad, is a major rail hub in the region, and each day thousands of passengers pass through the station, many on their way to Moscow.
The restive region of Chechnya is also located in this southern portion of Russia.