Notorious terrorists Shamil Basayev and Aslan Maskhadov masterminded the September 2004 siege of a school in Beslan, the head of the federal parliamentary investigation commission said Wednesday. "Separatists Shamil Basayev, Aslan Maskhadov, Magomet Khashiyev and their associates, notorious for cruelty, masterminded the terrorist attack," Alexander Torshin said. "Foreign mercenaries, including notorious [Arab] terrorist Abu Dzeit, also played an active role in the attack."The parliamentary commission has concluded that the Beslan attack was designed to destabilize the situation in the entire North Caucasus, Torshin said. The commission head said preparations for the attack had begun back in August 2004, when a group of 34 terrorists was formed in the Malgobeksky district of Ingushetia, a republic in the North Caucasus. "The militants' well-coordinated actions point to a planned operation," Torshin said. But the Ingush branches of the Federal Security Service and the Interior Ministry failed to take sufficient measures to track down and arrest the terrorists, he said. The school siege lasted 3 days, leaving 331 people dead and 783 wounded.