SAINT PETERSBURG -  About 10 people were killed and several more injured Monday after an explosion rocked the metro system in Russia's second city Saint Petersburg , according to authorities, who were not ruling out a possible terror attack.

President Vladimir Putin said investigators were looking into all possible causes for the explosion - "accidental, criminal and first of all ... terrorist."

Pictures screened on national television showed the door of a train carriage blown out, as bloodied bodies lay strewn on a station platform.

Above ground, emergency services vehicles rushed to the scene at the Technological Institute metro station, a key transport hub in the city centre.

"For the time being, we can say with full confidence that nine people have died and over 20 people were injured, including some who were seriously injured," the spokesman for Russia's national anti-terrorism committee (NAK), Andrei Przhezdomsky, said in televised remarks.

Authorities in Saint Petersburg had previously given a death toll of "about 10 people."

The blast caused scenes of confusion, with traffic blocked on Moskovsky Prospect, a busy throughfare as emergency vehicles rushed to the station.

"My mom was in the metro , I don't know what's happened to her, I can't get hold of her," one woman, Natalia, told AFP outside the station as she was trying to make a phone call on her mobile.

Pensioner Vyacheslav Veselov told AFP he had seen four bodies at the Technological Institute station.

"A station attendant in tears called on the men to help carry the bodies," he said.

Przhezdomsky said the blast occurred at 2:40pm local time (1140 GMT) and that the NAK had already launched an investigation.

He said "the blast happened in a train carriage between the stations Technological Institute and Sennaya (Square)," which are next to each other.

The committee later confirmed that security services had found a device at the Vosstaniya Square metro station which didn't explode and "neutralised" it.

The metro network announced it was shutting down entirely after evacuating all passengers and Russia's Investigative Committee also began a probe into the blast .

The Moscow metro also tweeted that it was "taking additional security measures" as required by law in such situations.

NAK said in a statement carried by Russian news agencies that security was being stepped up at transportation hubs and crowded places across the country.

Putin, who was holding a meeting near Saint Petersburg in his official Strelna presidential palace, offered "condolences" to those hurt in the blast .

EU foreign policy chief Federica Mogherini wrote on Twitter she was following the story "together with all EU foreign ministers" gathered for a meeting in Luxembourg.

"Our thoughts are with all the people of Russia," she wrote.

While there was no immediate indication as to what caused the blast , Russia's security services have previously said they had foiled "terrorist attacks" on Moscow's public transport system.

And extremists have targeted Russia's public transportation systems in the past. In 2013, Russia was hit by twin suicide strikes that claimed 34 lives and raised alarm over security at the Sochi Winter Olympic Games.

A bombing at the main railway station of the southern city of Volgograd killed 18 people on while a second strike hit a trolleybus and claimed 16 lives.

A suicide raid on Moscow's Domodedovo airport claimed by Islamic insurgents from the North Caucasus killed 37 people in January 2011.

That strike was claimed by the Caucasus Emirate movement of Islamist warlord Doku Umarov.

Russia beefed up its security over the holiday period in the wake of the attack on the Berlin Christmas market that killed 12.

Russia has intervened militarily to bolster Syrian President Bashar al-Assad's forces in September 2015, turning the tables on the battlefield just as rebel forces were strengthening their hold on key areas.

Russian bombardments helped the regime retake rebel areas in the east of the northern city of Aleppo after four years of fighting.

More than 310,000 people have been killed in Syria since the conflict broke out in March 2011 with protests against Assad's rule.

 

APP