Russia arrests St. Petersburg bombing suspect

Russia's FSB Security Service said Saturday it has arrested the man who set off a homemade bomb in a St. Petersburg supermarket.

The suspect was not identified, nor did police provide any details about his motive. However, police said the man allegedly organized and carried out the attack on his own.

Earlier, the "Islamic State" (IS) militant group claimed responsibility for Wednesday's blast, which injured at least 14 people, some of them severely.

"A security squad of caliphate soldiers managed to plant an explosive device in one of the shopping centers in the city of St. Petersburg in the Crusader northwest Russia the day before yesterday," the group said in a statement carried by their Amaq news agency.

The group's claim could not be immediately verified.

Russian investigators said the bomb was "homemade" and contained shrapnel, saying its force was equivalent to about 200 grams (7 ounces) of TNT.

Read more: Putin calls St. Petersburg blast a terror attack

Authorities believe the device was planted in a security locker at the store's entrance. Russian supermarkets usually encourage their customers to leave their personal belongings and bags in such lockers, in order to combat theft. Russia's Gazeta.ru news website published a composite photo showing the attack's aftermath on Twitter.

'Terrorists' target Russia

Russia has supported Syrian President Bashar Assad's regime against the IS militia and other rebel groups in the Syrian civil war. The move has put the country in the crosshairs of the terror group. In the past, Russia has also been repeatedly targeted by the al-Qaida network and jihadists from Chechnya.

Addressing Russian soldiers who had participated in a Syrian campaign on Thursday, Russian President Vladimir Putin said the St. Petersburg blast was "a terrorist act."

With 5 million inhabitants, St. Petersburg is Russia's second-largest city, after Moscow, and it is also Putin's hometown. Earlier this year, a group linked with al-Qaida targeted the city's subway system, with 15 people losing their lives in a suicide blast. Less than two weeks ago, Putin called US President Donald Trump to thank him for the CIA's assistance in thwarting an IS plot in the city.

The US provided Russia with information that helped detain a "group of terrorists preparing explosions in St. Petersburg's Kazansky Cathedral and other busy sites in the city," the Kremlin said at the time.

law, dj/cmk (dpa, AFP, Interfax)