Close to 20 people are reported dead after a suicide bomb blast went off at a railway station in the city of Volgograd, central Russia, according to police.
Dozens of others were severely injured.
Volgorad experienced another suicide attack in October when a female suicide bomber killed at least six people when she attacked a bus, loaded with passengers.
Dozens of others were severely injured.
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| Police at the scene of the accident. |
Volgograd lies about 900km (560 miles) south of Moscow and 650km north of the North Caucasus.
Russian authorities are concerned militant groups could be ramping up violence in the run up to the the 2014 winter Olympic Games in the city of Sochi, which is due to start on 7 February.
No group claimed immediate responsibility for this explosion.