At least 12 people were killed on Thursday in a gas explosion in a housing block in the city of Novosibirsk in Siberia, Tass news agency said, in Russia's second fatal gas explosion in three days.
The agency cited local officials as saying another three people were missing. The regional health ministry earlier said the dead included a two-year-old child.
Russia's Investigative Committee, which is responsible for major crimes, said it had opened an investigation and detained two people who had performed gas maintenance work in the building several days before.
Video published by Russia's emergencies ministry showed a section of a multi-story residential building largely destroyed, with the building's facade missing. The ministry's head flew to Novosibirsk to oversee the response.
In a separate incident on Tuesday, at least five people were killed in a gas explosion that ripped through a five-floor building in the town of Yefremov, south of Moscow. Gas explosions are relatively common in Russia because of ageing infrastructure and lax safety regulations.
(Reporting by Felix Light and David LjunggrenEditing by Gareth Jones)