The organizer and perpetrator of the St. Petersburg supermarket bombing, which injured 18 people, has been detained, Russia’s Federal Security Service (FSB) said.

“On December 30, FSB identified and detained the organizer and immediate perpetrator of the homemade explosive device blast in St. Petersburg ‘Perekrestok’ supermarket,” the FSB press service said.

The blast occurred in the supermarket on Wednesday. The explosive device, which had an estimated power of 200 grams of TNT, was filled with additional lethal fragments. According to the latest information, 18 people were injured in the blast, and eight of them remain hospitalized.

The FSB did not provide details neither on the operation which led to the capture of the suspect, nor on the motives behind the blast. The suspect has been transferred to Russia’s Investigative Committee for further questioning.

“Investigators have begun working with the suspected perpetrator of St. Petersburg explosion, he is being interrogated now. The investigation intends to request his arrest,” Investigative Committee spokeswoman Svetlana Petrenko said.

Alleged St. Petersburg terrorist attacker caught on CCTV (VIDEO) https://t.co/ivDpAtNsKIpic.twitter.com/yaM4q1ZPVL — RT (@RT_com) December 28, 2017

Late Friday, Islamic State (IS, formerly ISIS) claimed responsibility for the attack.

A source close to the investigation told Interfax news agency that the suspect is a resident of St. Petersburg with hardline nationalist views. The suspect suffered from mental health problems and was under psychiatric observation, TASS reported citing a source.