MOSCOW, Jan. 3 (CGTN) -- The death toll from the collapse of a building in the Ural city of Magnitogorsk has risen to 33 and eight others are still missing, the TASS news agency reported.

The blast, initially thought to have been caused by a gas leak, damaged 48 apartments in a 10-story building in Magnitogorsk in the early hours on Monday.

Russian rescuers pulled a 10-month-old baby boy hurt but alive from the ruins of the building where he spent the night in sub-zero temperatures, 35 hours after the collapse.

"A New Year's miracle has occurred!" Russia's emergencies ministry said in a statement.

Authorities said the little boy had been reunited in hospital with his mother, who also survived the ordeal.

Emergency services posted a video of rescuers slowly prising apart concrete panels and pulling out the baby, who can be seen blinking, before running with him to an ambulance.

"The rescuers heard crying," Chelyabinsk regional governor Boris Dubrovsky wrote on the Telegram messenger service.

"The baby was saved by being in a cradle and warmly wrapped up."

The little boy survived temperatures that fell overnight to around -27 degrees Celsius, the TASS news agency reported.

He was in an "extremely serious" condition, with severe frostbite to his limbs, a head injury and multiple leg fractures, the health ministry said.

he Soviet-era apartment block in Magnitogorsk, a city best known for one of Russia's largest steel plants, had been home to about 1,100 people. Residents left homeless are being housed in a nearby school.

Investigators have opened a criminal probe into the accident, which the FSB security service said was the result of a gas explosion.

Such explosions are relatively common in Russia, where much of the infrastructure dates back to the Soviet era and safety requirements are often ignored.