Russia’s Federal Security Service (FSB) has detained ISIS-linked terrorists who were planning attacks on the Moscow public transport system and other crowded places in Moscow.

Following the analysis of the materials found in the detainees’ house outside Moscow, the FSB said that it was a dangerous peroxide-based explosive, also known as the ‘Mother of Satan.’ The same explosives were reportedly used by terrorists in a series of deadly attacks in Europe, including the Manchester suicide bombing in May, the Paris terrorist attack in November 2015, and the March 2016 attack in Brussels.

“We have taken samples. According to these samples it is triacetone triperoxide (TATP), a very dangerous initiate explosive,” a serviceman is heard saying in a video taken during the FSB operation.

The video features materials to produce a bomb stored in the house, as well as several grenades found in the basement and Kalashnikov assault rifles.

The FSB says it has suppressed “a terrorist group which was plotting to commit a series of terrorist attacks in places of mass gatherings, including those on transport and major shopping venues in Moscow.” The statement adds that the group was going to use “suicide bombers and high-powered explosive devices.”

Two suicide bombers, an explosives production specialist, as well as an Islamic State (IS, formerly ISIS/ISIL) emissary who masterminded the planned attacks were detained during a special operation in Moscow Region on Monday.

4 ISIS-linked terrorists plotting public transport attacks detained in Moscow – FSB https://t.co/xmarvfQqsW — RT (@RT_com) May 26, 2017

The FSB also discovered and neutralized an explosives production laboratory.

The attacks were being organized by ISIS leaders in Syria, including people on the international wanted list, according to the FSB.

The security agency also said that there was one Russian citizen and three citizens of Central Asian states among the detainees. Their names have not been disclosed so far.

In late May, the FSB detained four ISIS-linked terrorists who were also preparing to carry out attacks in the Russian capital. The terrorists also planned to go to Syria and fight alongside ISIS militants.

READ MORE: Suspected ISIS recruiter detained in Bashkortostan, Russia

Earlier in May, a suspected Islamic State recruiter was arrested Russia’s mainly-Muslim Republic of Bashkortostan.

Apart from fighting terrorist infiltrators at home, Russia has been assisting Syrian government forces against Islamic State and other terrorist groups in Syria since September 2015.