Up to 40 people are believed to be trapped under rubble in Magnitogorsk in temperatures lower than -18 degrees Celsius.

Rescuers are battling through the bitter cold in Russia‘s Ural Mountains looking for survivors after a gas explosion tore through a high-rise apartment building killing at least four people.

Officials have said up to 40 people could be trapped under the rubble, at least seven of them children, after the explosion on Monday collapsed a large section of the residential building in the industrial city of Magnitogorsk, some 1,700km east of the capital, Moscow.

State TV showed rescue workers combing through mangled heaps of concrete and metal at -18 degrees Celsius, but Russian officials acknowledged that the odds of finding anyone alive looked increasingly slim.

“The chances are reducing with time,” Health Minister Veronika Skvortsova said when pressed by reporters on the likelihood of finding the trapped survivors.

“But incredible stories do happen.”

Witnesses told Russian television that the explosion was strong enough to shatter the windows of nearby buildings.

“I woke up and felt myself falling. The walls were gone. My mother was screaming and my son had been buried,” a witness said.

President Vladimir Putin rushed to the city, where the blast left hundreds of residents homeless in freezing temperatures on New Year’s Eve, the biggest holiday of the year in Russia.

Plunging temperatures

Authorities said rescue teams were to work through the night, with local temperatures expected to plunge to -23C.

Officials warned that two more sections of the Soviet-era high-rise on Karl Marx Street were in danger of collapsing.

Located in the mineral-rich southern Urals region, Magnitogorsk, with a population of more than 400,000 people, is home to one of the country’s largest steel producers.

The high-rise was built in 1973 and was home to around 1,100 people. The other residents of the building were moved to a nearby school.

The local governor, Boris Dubrovsky, told Putin that authorities published the missing persons’ list in the hope they were somewhere else when the explosion happened and would report their whereabouts. He promised to quickly provide new apartments for those who were left homeless.

Investigators opened a criminal probe into the accident, with the FSB security service confirming the incident as a gas explosion.

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