At least 10 people were injured after an explosion at a supermarket in Russia’s St Petersburg on Wednesday, Reuters reported. The bomb was placed in a locker where shoppers leave their belongings.

The improvised explosive device contained 200 grams of TNT and was rigged with shrapnel to cause more injuries, AP reported quoting investigators.

“All possible versions of what has happened are being worked on,” Alexander Klaus, the head of St Petersburg’s investigative committee, told Reuters.

No one has claimed responsibility for the explosion at the supermarket chain Perekrestok, while a criminal investigation has been launched.

‘An act of terrorism’

Russian President Vladimir Putin on Thursday called the blast an act of terrorism. “You know that yesterday in St Petersburg a terrorist act was carried out,” Putin said at an awards ceremony in the Kremlin for Russian military service personnel who fought in Syria. “And that recently the Federal Security Service prevented another attempted terrorist act.”