Two powerful tremors shook a remote, earthquake-prone region of northwestern China, killing at least nine people and injuring dozens of others, the State Seismological Bureau said yesterday. Local officials reported collapsed houses and scores of minor aftershocks.

　　Another six people were seriously wounded and 37 more suffered light injures, according to the bureau.

　　Authorities also lowered water levels on two reservoirs in the area, saying they feared flooding after they spotted cracks on dams after the quakes.

　　The earthquakes - measured at magnitudes 6.1 and 5.8, respectively - hit a desert area of Gansu Province at 8:41 and 8:48 pm on Saturday, the State Seismological Bureau said.

　　The hardest-hit areas were Minle and Shandan counties near the city of Zhangye. The death toll, initially listed as four, doubled yesterday afternoon after four missing people were found in rubble of collapsed buildings. An additional death was reported later.

　　The two stricken counties are located in an earthquake-prone region called the Qilian Seismic Zone,swheresa mountain range of the same name bumps up against flatlands. Seismologists say a rupture in that range may be making the area more seismically active.

　　An 8.5-magnitude quake on the edge of that zone in 1920 killed 200,000 people, said Zhang Xiaodong of the State Seismological Bureau's analysis and forecast center. In 1954, a 7.3-magnitude quake in the zone rumbled through Shandan County, killing 50 people.

　　According to the Gansu Provincial Seismological Bureau, 30 percent of houses near the quakes' epicenter were damaged severely and 90 percent of buildings in Yaozhaizi, a small village in Yonggu Township, had collapsed.

　　The Ministry of Civil Affairs said over 10,000 residential rooms collapsed. It also said 3,000 head of livestock were either killed or hurt and that schools, grain warehouses and bridges were damaged.

　　The water release from the Shuangshusi and Zhaizhaizi reservoirs in Minle County began minutes after the quakes and continued through the night. Nearly 6 million cubic meters of water had been released by yesterday morning.

　　The region has experienced snow and below-freezing temperatures in recent days, lending urgency to relief efforts and the erecting of temporary shelters.

　　"Most people slept outside last night. They wanted to make sure their houses didn't collapse on them," said Lu Jinggui, a clerk at a curtain shop in Minle, the largest town in the county that bears its name.

　　She said the quake damaged her wall with cracks wide enough to insert a chopstick.

　　"I think everyone will be sleeping outside again tonight - just to be safe," she said yesterday.

　　Premier Wen Jiabao and Vice Premier Hui Liangyu ordered a "quick and full" response by the Ministry of Civil Affairs and asked for assistance from the nation's military.

　　The central government has earmarked 7 million yuan (US,000) as an initial emergency relief fund for the earthquake-hit counties.

　　The Ministry of Civil Affairs sent a task force to the disaster-stricken area.