Russian rescuers have now pulled 31 dead bodies from the rubble of a collapsed apartment block in the city of Magnitogorsk.
Around 10 people are still listed as missing, rescuers told Russian media.
An 11-month-old boy rescued on Tuesday is in a serious but not life-threatening condition after being flown to Moscow for treatment.
Officials believe a gas leak was to blame for the blast on New Year's Eve, one of the country's biggest holidays.
A day of mourning is being marked in Magnitogorsk, in the Urals region about 1,695km (1,053 miles) east of Moscow. The current temperature there is -15C, and it plunges further overnight.
The rescued baby, called Ivan, spent 35 hours in the freezing cold, and was reported to have severe frostbite to his limbs, a head injury and multiple leg fractures.
However, Health Minister Veronika Skvortsova told reporters on Wednesday that his head injury was minor and treatment had improved his blood circulation.
His mother also survived the suspected gas explosion.
The blast ripped through the first floor at 06:02 local time (01:02 GMT), bringing seven upper storeys crashing down. In all, 48 flats - home to 120 people - were wrecked.
There was also some damage to nearby sections of the housing block, built in 1973.
Investigators have not found any traces of explosive at the scene, and the FSB state security service is treating it as a gas leak accident.
However, a criminal investigation has been opened, for suspected criminal negligence.
In an apparently unrelated incident, an explosion destroyed a minibus near the apartment block on Tuesday night, killing three people. Investigators say the vehicle was carrying two gas canisters.
President Vladimir Putin spoke to officials at the scene on Monday and later met survivors.
How was Ivan found?
He was found wrapped in a blanket and in his cot.
"[We made sure there was] silence so we could hear if sounds were coming or not," rescuer Pyotr Gritsenko told Russian state TV channel Rossia 24.
"One of the rescuers in our group, Andrei Valman, heard a child crying near the adjacent apartment block, near the part that was still standing.
"After that, we stopped all our equipment in order to make sure again, and listened. When we said 'Quiet!' the baby reacted and went quiet too. When we said 'Where are you?' she started to react again.
"When we were certain, the head of our centre, who is more experienced, said 'This is where we'll work' and told us to start removing the rubble."
Initially rescuers had thought the baby was a girl.