MIANYANG, China - The Chinese government warned yesterday that as many as 1.2 million residents might be evacuated because they could be inundated by a swelling "barrier lake" formed by the May 12 earthquake.
The warning was issued hours after a Russian helicopter transported heavy machines over mountains in the northern part of Sichuan province and hundreds of Chinese soldiers carried in 10 tons of dynamite to contend with the barrier lake at Tangjiashan, about two miles upstream from the town of Beichuan.
The afternoon announcement, broadcast on local television, made for another jittery day in Mianyang, a region with a population of 5 million that includes some of the areas hit hardest by the earthquake, including Beichuan.
Hopes of a return to normal in the region were set back by Sunday's magnitude-6 aftershock, centered north of here, which killed eight people and destroyed 270,000 houses.
The flood warning yesterday said that if the entire barrier collapsed, about 1.2 million people would be ordered to move to higher ground, including some in central Mianyang. Tens of thousands of people were evacuated earlier.
The warning prompted some people to haul their tents to higher ground and others to flee Mianyang.
"Some of my friends are leaving town; they want to go as far away as possible," said Liu Decai, 35, a taxi driver who drove home after the broadcast to pack up jewelry and other valuables.
China's central government continued to stress the importance of resettling victims, restoring production and rebuilding devastated areas. About 5 million people were left homeless by the quake, which has left more than 65,000 dead, more than 306,000 injured and 23,150 missing.
As of Sunday, 5,914 patients had been moved from overcrowded hospitals in Sichuan province to medical centers elsewhere in the country, and 2,100 more were to be transferred, the Ministry of Health said.
Elsewhere in China, officials said yesterday that the country's one-child policy exempts families with a child killed, severely injured or disabled by the earthquake, which killed many only children.
Those families can obtain a certificate to have another child, said the Chengdu Population and Family Planning Committee in the capital of hard-hit Sichuan province.
With so many shattered families asking questions, the Chengdu committee is clarifying the one-child policy, a committee official said.
"There are just a lot of cases now, so we need to clarify our policies," said the official, who declined to elaborate.
Chinese couples who have more than one child are commonly punished by fines.
The announcement says that if a child born illegally was killed in the quake, the parents will no longer have to pay fines for that child - but that the previously paid fines wouldn't be refunded.
If the couple's legally born child is killed and the couple is left with an illegally born child younger than 18, that child could be registered as the legal child. That would give the child previously denied rights, including nine years of free compulsory education.
Officials are closely watching barrier lakes, about 35 of which formed when rivers were plugged by landslides triggered by the quake. Geologists worry that aftershocks or heavy rain could burst the barriers.
One of the largest and most threatening holds more than 4.5 billion cubic feet of water, the official New China News Agency said.
Last night, about 600 engineers and soldiers had gathered at the blockage of the lake and were planning to work through the night to remove debris from a sluice, the agency said. Soldiers also might set off small-scale explosions to help drain the water.
Don Lee writes for the Los Angeles Times. The Associated Press contributed to this article.