Rescue workers are combing through the rubble of the collapsed section of building, with officials fearing that up to 40 people could be trapped

Moscow (AFP) - Rescuers hunted for survivors on Monday after a gas explosion tore through a high-rise residential building in central Russia, killing at least four people and leaving dozens unaccounted for.

A large section of the building collapsed after the explosion around 6:00 am local time (1100 GMT) at the high-rise in the industrial city of Magnitogorsk, nearly 1,700 kilometres (1,050 miles) east of Moscow in the Ural mountains.

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.

Officials said four people were confirmed dead and five others, including two children, had been taken to hospital. But officials added that up to 40 people could still be trapped under the rubble.

Officials said four people were confirmed dead and five others, including two children, had been taken to hospital

National television showed rescue workers combing through mangled heaps of concrete and metal in temperatures of minus 18 Celsius (minus 0.4 Fahrenheit).

“I went out to have a cigarette at quarter-to-six,” a local man told Russian television. “There was a blast and a wave of fire… then people started running out.”

Other witnesses said 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,” said another witness.

Russian television showed a grim-looking Putin in a black winter jacket meeting with local officials. He was also shown donning a white coat and visiting a victim in hospital.

Russian President Vladimir Putin rushed to the city of Magnitogorsk, where dozens were feared dead in a building collapse

“It is in the character of our people, despite New Year’s festivities, to remember to think of the dead and wounded at this moment,” Putin said.

Senior officials, including the emergencies and health ministers, flew to Magnitogorsk to oversee the rescue operation.

Emergencies minister Yevgeny Zinichev told Putin that between 36 and 40 people could be trapped under the rubble. Regional governor Boris Dubrovsky said seven children were among the missing.

- Plunging temperatures -

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

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.

A map locating the city of Magnitogorsk in the Ural mountains in Russia

The high-rise was built in 1973 and was home to around 1,100 people. Residents were evacuated to a nearby school.

Volunteers offered money, clothing and essentials to the victims, and some said they were ready to provide temporary shelter to those in need.

Dubrovsky, the local governor, said authorities planned to buy apartments for people who had lost their homes.

Staff from the local Magnitogorsk Iron and Steel Works (MMK), one of the country’s largest steelmakers, took part in the rescue operation.

Officials warned that two more sections of the Soviet-era high-rise were in danger of collapsing

Billionaire Viktor Rashnikov, who controls the plant, called on city residents to help the victims.

“This is our common tragedy and pain,” he said in a statement, adding that MMK would provide financial assistance to those in need.

Investigators opened a criminal probe into the accident, with the FSB security service confirming the blast had been the result of 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.