Powerful heaters were deployed to warm the rubble as rescuers raced against time to find possible survivors of New Year's Eve gas explosion ripped through a 10-story building in Russia.
Officials acknowledged that the chances of finding further survivors were dwindling as temperatures dropped to minus 11 degrees overnight.
The rescue effort in the city of Magnitogorsk also had to be temporarily suspended Tuesday as rescue crews were faced with a risk of the apartment block collapsing further.
Most of its inhabitants were still sleeping at the time of the blast.
The heaters were brought in to prevent anyone trapped in the rubble from dying of hypothermia."
The chances are reducing with time," Health Minister Veronika Skvortsova responded curtly when pressed by reporters on the likelihood of finding survivors. "But incredible stories do happen."
Russian President Vladimir Putin flew into Magnitogorsk on Monday, visiting the scene and a hospital where injured residents were taken.
Putin spoke with a 13-year old boy who sustained head injuries and frostbite after spending an hour under the rubble before being rescued.
Another survivor, Yulia Gavrilova, recalled the harrowing moments of the collapse.
"We were sleeping and I woke up feeling I was falling down," she said. "I first thought I was dreaming it. Then I woke up for real and realized that I was standing outside, the wall was not there any longer. My mother was screaming that she couldn't breathe and my son was screaming from another corner."
Authorities have promised financial assistance and permanent accommodation for the victims and their families.
A region-wide day of mourning was scheduled for Wednesday.