"I took the weapons to those boys," a detainee confessed that his collaboration with the terrorists of the attack in Moscow. He is one of four arrested on Sunday in the North Caucasus region, who would have financed the attack on Crocus City Hall.

According to the FSB, the detainees - who were part of a terrorist cell - were preparing an attack in the Dagestan city of Kaspiisk, on the shores of the Caspian Sea. "We wanted to detonate a bomb in the middle of the crowd," said one of the detainees.