Six children were among the dead, the emergency situations ministry said in a statement, and four people were still unaccounted for.
Rescuers have been braving temperatures as low as minus 27 degrees Celsius (minus 16 degrees Fahrenheit) to search through mangled concrete and metal at the site in the Ural mountains city of Magnitogorsk.
Six people including two children have been rescued at the site, but no survivors have been found since Tuesday, when a 10-month-old boy was found in what officials described as a “New Year’s miracle”.
The explosion tore through the 10-storey building in the industrial city nearly 1,700 kilometers (1,050 miles) east of Moscow in the early hours of Monday.
The Soviet-era block was home to about 1,100 people and the explosion destroyed 35 apartments, leaving dozens homeless.
The emergencies ministry said work was continuing at the site on Thursday, with nearly 900 people involved in rescue and recovery efforts.
A bridge had been built to reach higher areas and one of the building’s walls was taken down as it was threatening to collapse on rescue workers.
Financial help for victims
On Thursday residents of other parts of the building would be allowed to enter their apartments, in half-hour stretches, to recover some belongings, the ministry said.
All the survivors were in a stable condition, said the office of Chelyabinsk regional governor Boris Dubrovsky, who visited several of them in hospital on Thursday.
Dubrovsky’s office said he had also approved new financial assistance to the victims, including payments of one million rubles ($14,500, 12,700 euros) to the families of those killed and 400,000 rubles for those injured.
Families who lost their apartments would receive payments of up 500,000 rubles, as well as being provided with new homes.
Financial assistance was also to be provided to help pay for funerals, the first six of which were to be held on Friday, the governor’s office said.
The explosion, which officials have said was likely caused by a gas leak, happened as most of the building’s residents were asleep.
Witnesses described a “wave of fire” and said the blast was strong enough to shatter windows in nearby buildings.
Investigators have launched a probe, but have said there is no reason to suspect foul play.
Gas explosions are relatively common in Russia, where much of the infrastructure dates back to the Soviet era and safety requirements are often ignored.
Located in the mineral-rich southern Urals, Magnitogorsk, with a population of more than 400,000, is home to one of Russia’s largest steel producers.