Rescuers are searching for survivors in the central Russian city of Magnitogorsk, where an explosion devastated a block of flats, killing at least four people.
Officials in the city, in the Urals region, say a gas leak caused the blast. About 40 people are missing.
President Vladimir Putin has arrived in the city to assess the situation.
The building was home to 120 people, and 48 flats collapsed in the blast.
It is a race against time to find survivors, as the temperature in the industrial city is -17C. Few if any are expected to be pulled from the rubble.
Russia’s Vesti news channel says officials have accounted for more than 50 of the block’s residents, including the victims.
At least 16 survivors have been evacuated from the scene, including seven children. Four injured people are in hospital.
The blast, at 06:02 local time (01:02 GMT) is thought to have ripped through the first floor, which houses some offices, and the seven storeys above then collapsed. Nearby flats were also damaged.
The city is about 1,695km (1,053 miles) east of Moscow.