MOSCOW (AFP) - A mysterious explosion on Sunday rocked the location for filming for the hugely-popular Russian equivalent of the television reality show Big Brother, wounding one security guard, reports said. Security guards early Sunday uncovered a suspicious rucksack placed just inside the perimeter fence on their morning round and the blast went off when they tried to move it, the ITAR-TASS news agency reported. "As a result one of the security guards received multiple flesh wounds and is currently in hospital," the spokeswoman for the investigative committee in the Moscow region, Irina Gumennaya told ITAR-TASS. The TNT channel programme - "Dom-2" (House-2) - has won huge popularity in Russia but also controversy with the contestants not shying away from explicit discussions or activities on camera. The compound where the hopefuls live is located in the Moscow region. The website said police had also carried out searches of their living quarters to ensure no further explosives were found there. The motive of the attack remains a mystery, said.