BISHKEK, May 24. /TASS/. More than 20 people were detained as part of a criminal investigation into the Crocus City Hall terror attack, the head of Russia’s security service FSB, Alexander Bortnikov, said.

"We are currently establishing the entire circle of those involved in this atrocity. More than 20 people have already been detained, including the immediate perpetrators and aiders," he told a meeting of the Council of Heads of National Security Enforcement Agencies and Special Services of the Commonwealth of Independent States (CIS), which opened in Kyrgyzstan’s capital Bishkek on Friday.

In the probe, the FSB has been assisted by its counterparts from Kazakhstan, Kyrgyzstan, Tajikistan and Uzbekistan, Bortnikov said. It has been established that preparations for the crime as well as funding, the attack itself and the departure of terrorists had been coordinated on the Internet by members of the Islamic State - Khorasan Province, a branch of the Islamic State terrorist organization outlawed in Russia, from Afghanistan and Pakistan, he maintained. "Two of the four perpetrators of the attack had arrived in Russia from Turkey way prior to the act of terrorism," he added. And after committing the crime, the terrorists were given clear instructions to make it to the Ukrainian border where a "window" had been prepared for them, Bortnikov recounted.

The terror attack on the Crocus City Hall concert venue in the city of Krasnogorsk just a stone’s throw from Moscow’s city limits was staged on the evening of March 22. According to the latest data, the terror attack claimed at least 144 lives. As many as 551 people were hurt.