ST. PETERSBURG, Russia Ten people were killed and more than 20 were injured when an explosion tore through a train carriage in a St.Petersburg metro tunnel on Monday in what authorities called a probable terrorist attack
Russian news media said police were searching for a man recorded on surveillance cameras who was thought to have been involved in the attack, which coincided with a visit to the city by President Vladimir Putin.
Private television station Ren TV broadcast grainy pictures, it said were captured by a camera on board a metro train of a middle-aged man with a beard, a long black coat and black hat.
Closed-circuit footage from a few minutes later showed him outside the station hit by the blast, looking at his telephone.
Russia has been the target in the past of numerous bomb attacks, frequently targeting public transport. Most were blamed on Islamist rebels from Russia's North Caucasus region. The rebellion there has been largely crushed, but security experts say Russia's military intervention in Syria has made Russia a potential target for Islamic State attacks.
There was no immediate claim of responsibility.
Soon after the blast happened at 2:40 p.m., ambulances and fire engines descended on the concrete-and-glass Sennaya Ploshchad station. One helicopter hovered overhead, then landed on a broad avenue to take away an injured passenger.
“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,” St Petersburg resident Leonid Chaika, who said he was at the station where the blast happened, told Reuters by phone. "Many were crying."
Interfax news agency cited unnamed sources as saying the bomb, packed with shrapnel, may have been hidden in a train carriage inside a briefcase. The National Anti-Terrorist Committee said an explosive device had been found at another station, hidden in a fire extinguisher, but had been defused.
The blast raised security fears beyond Russian frontiers. France, which has itself suffered a series of attacks, announced additional security measures in Paris.
Video from the scene showed injured people lying 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. (GRAPHIC - St. Petersburg metro blast tmsnrt.rs/2nwjj3y)
A huge hole was blasted in the side of a carriage and the door blown off, with metal wreckage strewn across the platform. Passengers were seen hammering at the windows of one closed carriage after the train had pulled into the station.
Russian TV said many had suffered lacerations from glass shards and metal, the force of the explosion maximized by the confines of the carriage and the tunnel.
Anna Sventik, a St Petersburg resident, was traveling on a metro train that passed through the same station moments after the blast.
"Our train slowed down a bit, and one woman started having hysterics when she saw the people lying on the platform, blackened, in some places with no clothes, burned," she told Reuters. "It was very scary."
ALL STATIONS CLOSED
Officials said earlier on Monday that the death toll from the explosion was 9, but the health minister later revised that upwards to 10 dead. Some were seriously injured.
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 Islamist militants. In 2002, 120 hostages were killed when police stormed a Moscow theater 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 has continued a hard line in suppressing rebellion.
Putin, who faces elections next year but has as yet no serious rivals, made no mention of the bombing during a brief appearance after talks in St. Petersburg with the Belarussian president.