Rescuers continued searching for survivors in the rubble of the damaged block of flats early on Sunday, after pulling eight people out alive and finding five victims, including a 4-year-old child. The building reportedly housed 21 people.
A fuzzy YouTube video showed the extent of the destruction, with nearly half of the building apparently blown off, including several flats from the upper floor.
Emergency workers had to observe several "minutes of silence" to try and detect survivors trapped under concrete blocks.
A total of 15 people have been evacuated, four of them hospitalized.
Thirteen residents have been rescued from the ruins, and three managed to exit the building on their own. The fate of at least two more residents remains unclear.
A strong smell of household gas was reported at the site immediately after the explosion. Witnesses recalled people crying for help from under the collapsed floor.
Two flats were completely destroyed by the explosion. It did not start a fire, however.
The regional investigative committee has launched an inquiry into the blast.
Comment: A couple of weeks ago at least three people died and 13 were injured after a powerful gas explosion ripped through a block of flats in central Russia.