GUIXI TOWNSHIP, China (CNN) -- More than 18,000 people are reported buried under rubble in just one earthquake-hit city of China as rescue teams battle through power cuts, mudslides and heavy storms in desperate efforts to reach them. The official death toll has now exceeded 12,000, according to official state media.
Rescuers pull a woman out from rubble at a school Tuesday in Juyuan, China.
An injured man stands outside his destroyed home in the town of Hanwang Tuesday.
President Bush said the United States is prepared to help China "in any way possible" in the quake's aftermath.A top U.S. aid official said Beijing had not yet requested assistance.The United States has search-and-rescue teams standing by in Virginia and California, said Ky Luu, the director of foreign disaster assistance for the U.S. Agency for International Development.Luu said Beijing has good disaster-response mechanisms of its own."The Chinese have a strong capability of responding," he said, adding that the United States doesn't want to displace the internal expertise. "There is a 72-hour window of opportunity and it may be best to support regional teams on the ground."Some 20,000 Chinese troops have been deployed to the region, while another 24,000 are scheduled to be airlifted to affected areas, Xinhua reported. Another 3,000 police officers have been activated."It looks like they've mounted a pretty monumental effort to do the best that they can there," said Kate Janie, director of Mercy Corps, a humanitarian group channeling disaster aid to the region through a partner agency. "I think the Chinese government will make very active, proactive, transparent steps in dealing with this."Zhenyao said 60,000 tents and 50,000 quilts have been dispatched to the disaster zone.Chengdu Shuangliu International Airport reopened Tuesday after authorities inspected its runways for damage following the quake, Xinhua reported. The resumption of air service gives the province additional links for funneling supplies into the badly battered region.A 40-car freight train, carrying 13 tankers full of gasoline, derailed and caught fire Monday in Gansu province, officials said, according to state-run media, cutting the Baoji-Chengdu railway. Monday's quake shook the ground in Beijing, 950 miles (1,528 km) away. Residents of the capital, which hosts this year's Olympic Games in August, said they felt a rolling sensation that lasted about a minute. It resulted in the evacuation of thousands of people from Beijing buildings.