Temperatures in Magnitogorsk were expected to plunge to minus 23 Celsius on New Year's night, the biggest holiday of the year in Russian Federation.
An entire section of the 12-storey residential building collapsed when a gas explosion tore through the high-rise in the industrial city of Magnitogorsk almost 1,700kms (1,050 miles) east of Moscow in the Ural mountains.
The blast reportedly happened at around 6am local time, when many people were sleeping on what is a Russian public holiday.
Almost 1,400 rescuers searched for people who might be buried under building debris in temperatures of -17 degrees Celsius (1.4 degrees Fahrenheit).
Local authorities initially said 68 people registered as residents in the collapsed section of the building were missing, but later tracked down some of them.
Emergency officials said they were racing against time since the frigid weather reduced the chances of finding anyone alive.
The whereabouts of 28 people have been established but the fate of almost 70 was unclear.More news: Dipika Kakar stumps Sreesanth to win Bigg Boss 12
The Kremlin said President Vladimir Putin had been "immediately notified of the tragedy in Magnitogorsk".
The head of the Tajik diaspora in Magnitogorsk, Abulmajid Sharipov, told RFERL that a Tajik family of five was living in an apartment in the collapsed part of the building.
Senior officials, including the emergencies and health ministers, flew to Magnitogorsk to oversee the rescue operation.
Emergency service workers are trying to evacuate trapped residents.
Gas explosions in Russian homes are fairly common, most of which are blamed on neglect of safety rules or poor maintenance.
Dubrovsky, the local governor, said authorities planned to buy apartments for people who had lost their homes.