Russia’s Federal Security Service, or FSB, said it prevented an attack on a synagogue in Moscow, Russian state news agencies reported on Thursday.

“The Russian Federal Security Service has suppressed the criminal activity of a Central Asian national who was planning to perpetrate a terrorist attack on a Jewish religious institution in Moscow at the time of a mass gathering there,” FSB said in a statement, according to Russian state media outlet Interfax.

The statement added that a “Central Asian national” who was plotting the attack was “killed during detention.”

The FSB also said that the man had been previously incarcerated and became radicalized during his imprisonment, according to state-controlled TV news network RT International. He was eventually released and came to Russia in 2023.

The suspect reportedly was surveilling the synagogue and had purchased the materials to make explosives when he was caught and arrested on Wednesday.

According to media outlet Ynet, Russia’s chief rabbi, Berel Lazar, thanked the FSB for its work in preventing the attack.

This comes weeks after the deadliest terror attack on Russian soil in recent history, which occurred in Moscow’s Crocus City Hall music venue and left 139 dead.

The Islamic State group’s Afghanistan affiliate claimed it carried out the attack, and US intelligence said it had information confirming the group was responsible.

That attack followed an early March incident in which the FSB reportedly prevented another attack on a synagogue in Moscow that was plotted by an Islamic State cell.

The FSB said that the members of the organization had been planning “to commit a terrorist act against one of the Jewish religious institutions in Moscow,” the RIA news agency quoted the report as saying.

Attackers opened fire during the attempted arrest, and were “neutralized by return fire,” the FSB said.

Agencies contributed to this report.