Russian rescuers were on Monday searching for people trapped under the rubble of a city apartment block that partly collapsed in a suspected gas blast, killing at least three, RIA said.
Russia's emergencies ministry told the news agency that four people had been recovered alive from the nine-storey building in Magnitogorsk, an industrial city some 1,700 km (1,050 miles) east of Moscow in the southern Urals.
Footage obtained by Reuters from Verstov.info, Magnitogorsk's local information agency, shows smoke rising from collapsed rubble well into daylight.
News agency TASS said 79 people were unaccounted for, quoting Chelyabinsk regional Deputy Governor Oleg Klimov. The emergencies ministry said the blast, probably caused by a gas leak, damaged 48 apartments.
RIA said it ripped through the building at around 0600 a.m. (0100 GMT) when many residents were asleep. Monday is a public holiday in Russia.