An eight-year-old girl found the bodies of her parents, brother and grandmother in a basement after they were poisoned by gas from rotting potatoes.
A Russian news agency reports that eight-year-old Maria Chelysheva's family were killed one by one after entering a cellar where they stored potatoes for the winter. Relatives are caring for the orphaned girl.
Her father, Mikhail, 42, was first to enter the cellar, not realising the potatoes had become seriously rotten.
He fainted from the noxious fumes, and soon afterwards died, police said. When he failed to re-appear, his worried wife Anastasia, 38, went to look for him in the dark and was also overcome by the poisonous gas.
Next the couple's 18 year old son Georgy went in search of his parents, only to suffer the same tragic fate as his mother and father after inhaling the highly toxic fumes.
Anastasia's mother Iraida, 68, called a neighbour to say there was something suspicious and to plead for help.
But before assistance arrived, she also went into the cellar, suffocated from the gas, and collapsed and died like the others, say police. It is understood that as she went in, she left the door open, allowing the fumes to disperse.
When Maria entered the cellar, she found the bodies of her whole family on the cellar floor.
The shocking case was at Laishevo, a town near Kazan, in the Russian republic of Tatarstan on the Volga River.
"They all died of gas poisoning which has accumulated in the basement as a result of badly rotting potatoes," said a local investigator.
"The poor girl found the bodies of the deceased."