Russian police are focusing on an Islamic suspect filmed by surveillance cameras inside a St. Petersburg subway station right before the bombing which killed at least 12.

The suspect, who had a beard and wore a Muslim cap, left his briefcase on the subway car and then quietly left the station, according to Russian media.

The police, however, did not exclude the possibility the man was a decoy meant to mislead the investigation.

Earlier, Russian President Vladimir Putin said all possible causes for the explosion are being investigated, including terrorism.

“The causes of this event have not been determined yet, so it’s too early to talk about [possible causes],” he said. “The investigation will show. Certainly, we will consider all variants, common, criminal, first of all, of a terrorist nature.”

It’s likely Russian officials are considering a deeper cause given that Putin was nearby giving a speech at a media forum in St. Petersburg.

“The explosion happened between the Sennaya Ploshchad station and Tekhnologichesky Institut at around 2:40pm local time, Russia’s National Anti-Terrorism Committee said,” reported RT. “The blast was caused by an unidentified explosive device, officials announced, adding that all metro stations in St. Petersburg have been closed.”

“The metro is basically fully evacuated, according to Russia’s National Anti-Terrorism Committee.”

And as Infowars reported earlier, ISIS supporters were quick to celebrate the attack on social media.

Al Jazeera Arabic’s Facebook coverage of the attack in particular was flooded with positive comments and ecstatic emoticons.

“God more of explosions in the metro + God more… Russians in metro + drinks all commentators today on me,” one supporter said in broken English. “…Congratulations hidayah! Grrr!”

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