At least 10 people were killed and 20 were injured when an explosion tore through a train carriage in a St Petersburg metro tunnel on Monday, and Interfax news agency said the blast may have been caused by an explosive device hidden in a briefcase.Two suspected terrorists are on the run after a nail bomb planted in a St Petersburg train ripped through the carriages - killing at least 10 people and injury 50 today.
Several Russian media outlets have released the CCTV picture of the bearded suspect who was wearing a long, black top and a hat blamed for causing the carnage by detonating a bomb that was packed with shrapnel.
The terrifying incident took place on a train that was travelling between Sennaya Ploshchad and Sadovaya metro stations. A second explosive device disguised as a fire extinguisher was found and defused in a nearby station.
Nobody has claimed responsibility for the explosion, but previous attacks on Russia have been blamed on ISIS and Chechens.
A search warrant has now been issued for two people in connection with the attack - one for planting the bomb which detonated at Sennaya Ploshchad and the other for leaving an explosive device at Ploshchad Revolutsii station.
A source said: 'Two people are being sought on suspicion of planning the blasts, one of whom is thought to have placed the explosive device in the metro wagon and the second person for leaving a bomb at the metro station Ploshchad Revolutsii.'
Dozens have been injured, including at least three children, as it was reported the man left a briefcase on a train before moving carriages moments before the deadly blast.
The agency, quoting unnamed sources, said surveillance cameras had captured images of what it called the organisers of the explosion, which hit St Petersburg as President Vladimir Putin was visiting the city.
Russia's National Anti-Terrorist Committee said another explosive device had been found at a different metro station, but it had been made safe.
Putin, in another part of the city for a meeting with Belarus's leader, was initially cautious. He said he was considering all possible causes, including terrorism.
"I appeal to you citizens of St Petersburg and guests of our city to be alert, attentive and cautious and to behave in a responsible matter in light of events," St Petersburg Governor Georgy Poltavchenko said in an address.
Video showed injured people bleeding on a platform, some being treated by emergency services and fellow passengers. Others ran away from the platform amid clouds of smoke, some screaming or holding their hands to their faces.
A huge hole was blown open in the side of a carriage with metal wreckage strewn across the platform. Passengers were seen hammering at the windows of one closed carriage.
Russian TV said many had suffered lacerations from glass shards and metal, the force of the explosion maximised by the confines of the carriage and the tunnel.
“I saw a lot of smoke, a crowd making its way to the escalators, people with blood and other people's insides on their clothes, bloody faces. Many were crying,” St Petersburg resident Leonid Chaika, who said he was at the station where the blast happened, told Reuters by phone.
All stations closed
St Petersburg emergency services at first said that there had been two explosions. But a source in the emergency services later said that there had been only one but that the explosion had occurred in a tunnel between stations.
The blast occurred at 2:40pm., well shy of the evening rush hour.
Authorities closed all St Petersburg metro stations. The Moscow metro said it was taking unspecified additional security measures in case of an attack there.
Russia has been on particular alert against Chechen rebels returning from Syria, where they have fought alongside Islamic State, and wary of any attempts to resume attacks that dogged the country several years ago.
At least 38 people were killed in 2010 when two female suicide bombers detonated bombs on packed Moscow metro trains.
Over 330 people, half of them children, were killed in 2004 when police stormed a school in southern Russia after a hostage taking by militants. In 2002, 120 hostages were killed when police stormed a Moscow theatre to end another hostage-taking.
Putin, as prime minister, launched a 1999 campaign to crush a separatist government in the Muslim southern region of Chechnya, and as president continued a hard line in suppressing rebellion.Bloodied passengers were left strewn across the platform in the Russian city as emergency services scrambled to save those wounded by the bomb and the resulting shards of glass and twisted metal.
Vladimir Putin is in his hometown of St Petersburg today for talks with the president of Belarus and confirmed 'there are dead and injured', offering his condolences to the families of those killed.
The Kremlin leader, who wanted to visit the scene in the aftermath of the attack but was held back by security services, said: 'I have already spoken to the head of our special services, they are working to ascertain the cause of the blasts.
'The causes are not clear, it's too early. We will look at all possible causes, terrorism as well as common crime.'
Interfax news agency cited an unidentified source who says the suspect in Monday's blast might have left the explosive device in a bag.Russian online news outlet Fontanka published the grainy photo which shows a middle-aged man who entered Petrogradskaya station 20 minutes before the blast.
Interfax news agency earlier quoted a source as saying that surveillance cameras had captured photos of the blast suspect.
At this stage it is not clear whether or not the suspect was wearing the hat and gown as a disguise.
Kremlin spokesman Dmitry Peskov denied earlier speculation that President Putin was due to pass by the Sennaya Metro station around the time of the blast.
The explosion happened between the Sennaya Ploshchad station and Tekhnologichesky Institut at around 2.40pm local time, Russia's National Anti-Terrorism Committee said. A witnesses told Russia's Life News: 'People were bleeding, their hair burned. We were told to move to the exit, because the movement stopped. People just fled.
'My girlfriend was in the next car that exploded. She said that he began to shake. When she came out, she saw that people were mutilated.'
A male eyewitness said: 'It's just like a war here. Every special service is here, the FSB, police, and multiple - really a lot of them - ambulances.
'I don't think I've ever seen to many paramedics in my life. Something completely horrible is happening here.'
Eight bodies were recovered from the carriage while two more were found on the platform or were in the tunnel.
Earlier reports indicated a backpack had been thrown onto the train and witnesses also suggested there had been multiple explosions, but officials confirmed just the one blast.
Russian security agencies did find an explosive device at a different metro station in central St Petersburg and made it safe, the National Anti-Terrorist Committee said in a statement.
The device was found at the Ploshchad Vosstaniya metro station, a different location from where a blast earlier took place.
Other witnesses also described a man leaving a briefcase on one carriage before moving to another just seconds before the huge explosion.
As reports of the suspected terror attack trickled through to the capital, Moscow heightened its security and local reports suggest three metro stations - Nagatinskaja, Savelovskaya and Ugrezhskaya (CIP) - were cordoned off due to suspicious packages.
