Manhunt underway for two suspects after Russian metro blast
A bomb blast tore through a subway train in St Petersburg, killing 10 people and injuring about 40 as President Vladimir Putin visited the city, authorities have said.
Hours later, police found an unexploded device in one of St Petersburg's busiest subway stations, sending a wave of anguish and fear through Mr Putin's home town.
There was no immediate claim of responsibility for the attack, but Russian trains and planes have been targeted repeatedly by Islamic militants, mostly connected to the insurgency in Chechnya and other Caucasus republics.
A police hunt is now underway for two suspects who are believed to have been involved.
Russian news media said police were searching for a man recorded on surveillance cameras who was thought to have been involved in the attack.
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.
"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'," the source told Interfax
The last confirmed attack was in October 2015 when Islamic State militants downed a Russian airliner heading from an Egyptian resort, killing all 224 people on board.
The December 25 crash of a Russian plane carrying Red Army choir members near the southern city of Sochi is widely believed to have been due to a bomb, but no official cause has been stated for the crash that killed 92 people.
The blast on Monday hit the St Petersburg train as it travelled between stations at about 2.20pm local time.
The driver chose to continue on to the next station, Technological Institute, a decision praised by Russia's Investigative Committee as aiding evacuation efforts and reducing the danger that passengers would die by trying to walk along the subway's electrified tracks.
After a few hours of differing casualty tolls, health minister Veronika Skvortsova said 10 people died from the blast.
City health authorities said 43 others were taken to hospital.
Witnesses said the blast spread panic among passengers, who ran towards the exits of the station, which is 40 metres (130ft) underground.
"Everything was covered in smoke, there were a lot of firefighters," Maria Smirnova, a student on a train behind the one where the blast went off, told the Dozhd television channel.
"Firefighters shouted at us to run for the exit and everyone ran. Everyone was panicking."
The entire St Petersburg subway system, which serves some two million passengers a day, was shut down and evacuated.
Russia's National Anti-Terrorist Committee said security was immediately tightened at all of the country's key transportation sites, and Moscow officials said that included the subway in the Russian capital.
Mr Putin, speaking on television from Constantine Palace in the city, said investigators were looking into whether the explosion on the train was a terror attack or if it had some other cause.
He offered his condolences to the families of those killed.
Within two hours of the blast, Russian authorities had found and deactivated another bomb at a separate busy St Petersburg subway station, Vosstaniya Square, the anti-terror agency said.
That station is a major transfer point for passengers on two lines and serves the railway station from which most trains to Moscow depart.
Russian law enforcement agencies confirmed the Vosstaniya Square device was rigged with shrapnel and the Interfax news agency said it contained up to 1kg (2.2lbs) of explosives.
Social media users posted photographs and video from the Technology Institute subway station showing injured people lying on the floor outside a train with a mangled door.
Frantic commuters were reaching into doors and windows, trying to see if anyone was there, and shouting: "Call an ambulance!"
St Petersburg, Russia's second-largest city with more than five million residents, is the country's most popular tourist destination but there was no immediate information on whether any foreigners were among the victims.
Nataliya Maksimova, who was running late for a dental appointment, entered the subway near the explosion site shortly after the blast.
"If I hadn't been running late, I could have been there," she said.
Mr Putin was in St Petersburg on Monday to meet with Belarusian President Alexander Lukashenko, and went ahead with the talks after appearing on Russian television to speak about the incident.
"Law enforcement agencies and intelligence services are doing their best to establish the cause and give a full picture of what happened," Mr Putin said.
Russian transport facilities have previously been the target of terror attacks.
Suicide bombings in the Moscow subway on March 29 2010 killed 40 people and wounded more than 100 people.
Chechen rebel leader Doku Umarov claimed responsibility for the attack by two female suicide bombers, warning Russian leaders that "the war is coming to their cities".
A Moscow-to-St Petersburg train was also bombed on November 27 2009 in an attack that left 26 dead and some 100 injured.
Umarov's group also said he ordered this attack.
Russian airports have also been hit by attacks.
On January 24 2011, a suicide bomber blew himself up at Moscow's Domodedovo Airport, killing 37 people and wounding 180.
The same airport in August 2004 saw Islamic suicide bombers board two planes and bring them down, killing a total of 90 people.
President Donald Trump later called the deadly bomb blast an "absolutely a terrible thing".
President Trump spoke before a working lunch with Egypt's President Abdel-Fattah el-Sissi.
He said of the attack "it's happening all over the world".