An explosion rocked an apartment building in Russia's Ural Mountains Monday, emergency officials said. The Interfax news agency reported that the blast was caused by gas and that several people were hospitalized. A police official said people remained under the rubble and children could be heard after the explosion in a three-story building in the Sverdlovsk region city of Kushva, Interfax reported. A regional emergency department official said an explosion occurred but had no information about the cause or casualties. "There are people beneath the rubble, and children's cries for help can be heard right now," Interfax quoted regional police spokesman Valry Gorelykh as saying. The agency said the blast was caused by gas.