China today rushed more troops and air-dropped relief supplies in areas cut off near the epicentre of the devastating earthquake in southwest Sichuan province as the toll mounted to nearly 20,000 with thousands of people still buried, trapped or missing. As troops reached the quake-battered areas, the state media reported that the death toll in Mianyang city alone rose from 3,629 to 5,540 with 18,486 more buried and 1,396 missing. In Yingxiu of Wenchuan County, only 2,300 persons were believed to have survived out of 10,000 residents, official Xinhua news agency said.