The authorities said five people were hospitalized with injuries, and 38 other residents remained unaccounted for in the accident in Magnitogorsk, a city of 400,000 about 1,400 kilometers (870 miles) southeast of Moscow. He was also shown donning a white coat and visiting a victim in hospital.
Authorities said rescue teams were to work through the night, with local temperatures expected to plunge to minus 23 Celsius.
The blast tore through the building at around 6 a.m. (0100 GMT) when many residents were asleep, RIA news agency reported.
"It is in the character of our people, despite New Year's festivities, to keep in mind to think of the dead and wounded at this moment", Putin said. Monday was a public holiday in Russian Federation.
The emergencies ministry said the blast, probably caused by a gas leak, damaged 48 apartments.
At least four people are dead and dozens missing after a suspected gas explosion ripped through an apartment building in southern Russian Federation on Monday, state media reported.
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The Union-Tribune, a former Tribune Publishing newspaper, still uses the company's production software. A spokeswoman for the Department of Homeland Security said it was studying the situation.
Russian news agency TASS reports that six people have been pulled out of the rubble, of which three died, and that 79 were missing.
Senior officials, including the emergencies and health ministers, flew to Magnitogorsk to oversee the rescue operation.
Dubrovsky said later that some apartments were leased and in general, 120 people, were housed in the collapsed part of the building.
According to the regional government, Russian Health Minister Veronika Skvortsova and Emergency Situations Minister Yevgeny Zinichev have arrived in Magnitogorsk and are now at the site.
Local resident Anna Koroleva told Echo of Moscow radio that the explosion shattered windows of nearby buildings.
There have been several similar incidents in Russian Federation in recent years due to aging infrastructure and poor safety regulations regarding gas usage.