The blast sparked a violent fire that was finally put out late afternoon, according to Oleg Grebenyuk, an official at the local emergency situations office.
At least one person was killed on Sunday and several others were missing after a gas explosion ripped through an apartment block in the southern Russian city of Volgograd, authorities said.
"One body has been recovered," Leonid Belyaev, a minister with the emergency situations ministry, was cited by Russian news agencies as saying.
"We believe five other deceased persons, including the three residents of the apartment where the explosion happened and one person who was their guest, may be found under the rubble."
Officials previously gave a toll of 11 people injured and eight missing.
"Eleven people are at the hospital, including two children and an elderly woman. Three people are in a serious condition," health ministry spokesman Oleg Salagai told agencies.
Regional governor Andrey Bocharov told Interfax news agency earlier that eight people were missing, with the emergency situations ministry saying a search operation was underway.
"It is possible they were elsewhere at the time of the explosion," a senior ministry official said.
The explosion happened around noon (0900 GMT) on the seventh floor of the nine-storey building in northwest Volgograd, Russian media said, tearing through the building to the first floor.
The blast sparked a violent fire that was finally put out late afternoon, according to Oleg Grebenyuk, an official at the local emergency situations office.
The head of the Volgograd district where the blast occurred, Sergei Tatsy, told state television that 36 apartments had been destroyed in total, leaving some 100 people homeless.
Residents will be temporarily rehoused in local schools, the emergency situations ministry said.
Russia's investigation committee, which has launched an inquiry, said the two injured children were aged five and seven and their lives were not in danger.
Gas explosions are common in Russia. The last serious accident, in February 2012, killed 10 people in the southern city of Astrakhan, destroying the entire side of a nine-storey building.