MOSCOW: Russia’s FSB security service has said that four people arrested Sunday in a foiled “terror” plot had provided money and arms for the deadly attack on a Moscow concert hall last month.

More than 140 people were killed when gunmen stormed the Crocus City Hall venue on March 22 before setting the building on fire in the most fatal attack in Russia for two decades.

The FSB said in a statement on Monday that it had arrested a group of four a day earlier in the southern Dagestan region who “were directly involved in the financing and supply of terrorist means to the perpetrators of the terrorist act carried out on 22 March in the Crocus City Hall in Moscow.”

On Sunday, Russia’s national anti-terrorism committee said it had apprehended three people who were “planning to commit a series of terrorist crimes.” The FSB said Monday that four foreign citizens had been arrested in the operation in the regional capital Makhachkala and the nearby town of Kaspiysk.