Sunday’s explosion rocked Volgograd-1 station at around 12:45 (08:45 GMT) at a time of year when millions of Russians are travelling to celebrate the New Year.
A nearby security camera facing the station caught the moment of the blast, showing a bright orange flash behind
the station’s main doors.
The explosion shattered windows and sent debris and plumes of smoke from the station entrance.
The first cameras on the scene showed bodies lying outside, and inside, twisted metal and singed, pock-marked walls.
Motionless bodies were laid out in the station forecourt while ambulances rushed those hurt to hospital.
About 40 people are said to have been injured, including a nine-year-old girl whose mother was killed in the attack.
“People were lying on the ground, screaming and calling for help,” a witness, Alexander Koblyakov, told Rossiya-24 TV.
“I helped carry out a police officer whose head and face were covered in blood. He couldn’t speak.” President Putin ordered law enforcement agencies to take “all necessary security measures” in the bomb’s aftermath, said a Kremlin spokesman.
He ordered the most gravely injured victims to be flown to Moscow for treatment.
Security will be stepped up at railway stations and airports. No group has yet claimed responsibility for the blast, but a spokesman for Russia’s Investigative Committee, Vladimir Markin, said the incident was being treated as an act of
An Islamist insurgency in the North Caucasus region has led to many attacks there in recent years. Insurgents have also attacked big Russian towns.
This attack shows that the bombers do not need to attack Sochi directly to attract international attention – any target in Russia will do, says the BBC’s Daniel Sandford in Moscow.
Volgograd lies about 900km (560 miles) south of Moscow, 650km north of the North Caucasus and 700km north-east