A gas-system explosion on the eighth floor of a building in Russia Friday killed one person, injured 11 and caused heavy damage, an official said. Nikolai Nikolauchuk, mayor of the West Siberian city of Tomsk said the blast and a subsequent fire destroyed a wall, two balconies and caused damage in two apartments, RIA Novosti reported. Investigators said the explosion was caused by a malfunction in a gas-supply system.