The gas exploded on the third floor of the nine-storey building, causing the collapse of the entire structure, local police said.
Seven people, including two children, have been hospitalized, according to Interfax news agency.
Police suspected the gas explosion was made deliberately by a mentally unstable resident who has attempted to commit suicide, said Sergei Bobrov, a senior investigator at the local Investigative Committee.
However, Vladimir Markin, spokesman for Russian Investigative Committee, told Itar-Tass news agency that a preliminary inquest indicated that the incident might have been caused by gas explosion in a shop on the ground floor.
(C003)
Editor: Ella Syafputri
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