Chinese authorities had evacuated nearly 200,000 people by early Saturday and warned more than 1 million others to be ready to leave quickly as a lake formed by a devastating earthquake threatened to breach its dam. Hundreds of Chinese troops have been working around the clock to drain Tangjiashan lake in Sichuan province. The lake formed above Beichuan town in the Mianyang region when a hillside plunged into a river valley during the May 12 quake that killed more than 68,000 people. The official Xinhua News Agency said work on a runoff channel had been completed. It quoted Yue Xi, deputy chief of the water and electricity section of the People's Armed Police, as saying water was expected to be discharged between Sunday and Tuesday. Xinhua said 197,477 people were evacuated to safe ground by Saturday morning. It did not say how the exact number was arrived at, and many of the people may have moved just short distances to higher areas. The news agency said Tan Li, the Communist Party chief of Mianyang, had issued another order that calling for all 1.3 million people in the area to be evacuated if "the barrier of the quake lake fully opens" and floods the area. FIND MORE STORIES IN: Xinhua News Agency | Communist Party | Sichuan | China | President Hu Jintao | Wang | Chen | Shaanxi | Zhang | Beichuan | Armed Police | Tangjiashan An official with the press office of Mianyang City Quake Control and Relief Headquarters, who would give only her surname of Chen, said Saturday's drill would involve testing the command system of various levels of government officials to ensure that any order to evacuate