The revolt of the Czechoslovak Legion broke out in May 1918, and the legionaries took control of Chelyabinsk in June. Simultaneously Russian officers' organisations overthrew the Bolsheviks in Petropavlovsk (in present-day Kazakhstan) and in Omsk. Within a month the Czechoslovak Legion controlled most of the Trans-Siberian Railroad between Lake Baikal and the Ural regions. During the summer Bolshevik power in Siberia was eliminated. The Provisional Government of Autonomous Siberia formed in Omsk. By the end of July the Whites had extended their gains westwards, capturing Ekaterinburg on 26 July 1918. Shortly before the fall of Yekaterinburg on 17 July 1918, the former Tsar and his family were murdered by the Ural Soviet to prevent them from falling into the hands of the Whites.