The members were convicted of the 2010 fatal stabbing of eight adults and the strangling of three children in the home of a farmer in the Krasnodar region, RIA Novosti reported Saturday.
A fourth child died from smoke inhalation after the gang set the house on fire, court documents said.
The leader of the gang blamed the farmer for the death of his brother.
The gang's attorney, Vyacheslav Dmitriyenko, said he would appeal the verdict.
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