"The commission has officially established that the explosion was caused by the actions of terrorists, based on numerous examinations and testimonies [of former hostages]," Alexander Torshin said.
A total of 331 people, including 186 children, were killed at Beslan's School No.1 in the North Caucasus republic of North Ossetia in September 2004. More than 700 people were wounded.
On the third day of the hostage crisis, explosions were heard from the school gymnasium, around the time that gunmen opened fire from within the building. A shootout between hostage-takers and troops ensued, and special forces stormed the building. The media circulated various versions as to the cause of the first explosion.
Torshin said that according to the report, the operation headquarters set up when the siege began acted within the law, and took all possible measures to save lives.
He said Aslan Maskhadov, Shamil Basayev and Abu-Dzeit had orchestrated the terrorist attack, but have all been killed.
"Just punishment was dealt to all organizers and participants of the Beslan terrorist attack. The odious ringleaders of the terrorist underground who planned this act - Maskhadov and Basayev, Abu-Dzeit and Khashiyev - have been liquidated. The 31 terrorists who seized the school were killed. Only [Nurpashi] Kulayev, who was given a life sentence, is still alive," Torshin said.
The commission's report also blamed local police for the tragedy, saying they did not take appropriate measures to prevent the attack.
"The terrorist act was not prevented, because local police did not follow the regulations established by the Russian Interior Ministry," the report said.
Police officers were not present at the school's start-of-term ceremony on September 1, 2004, when terrorists took 1,128 hostages, the document said.