MOSCOW, Dec. 31 (Xinhua) -- Up to 79 people are missing and the death toll has increased to three after a gas explosion rocked a building in the Russian city of Magnitogorsk in the Ural Mountains, Chelyabinsk Region's deputy governor Oleg Klimov said Monday.

"Three alive and three dead were taken from under the debris," Klimov was quoted by Sputnik news agency as saying, adding that the fate of the 79 missing people remains uncertain.

A criminal investigation has been opened, said Klimov.

The suspected natural gas explosion occurred at around 6 a.m. local time (0100 GMT) on Monday. A total of 48 apartments in the 10-story building were damaged in the blast.