On February 14, the roof of Moscow's Transvaal Park caved in killing 26 people. 59 victims are undergoing treatment in hospitals.
"Experts did not find explosive particles on the samples from the scene." This means that one of the bearing columns collapsed for technical reasons, according to the source.
Moscow Deputy Prosecutor Vladimir Yudin said earlier that the investigating team would conduct a technical expertise at the scene.
"We are not treating the accident as a terrorist act, however we will take samples at the scene and conduct a test to end suspicions and talk about a terrorist act," said Mr Yudin.
Mr Yudin refuted media reports claiming the water park collapse had been perpetrated by terrorists. "Investigators have no evidence to this effect," he said.
The Moscow Prosecutor's Office has opened criminal proceedings according article 109 of the Russian Criminal Code (reckless killing).