Rescuers searched Monday for 17 workers missing after a subway tunnel they were building in eastern China caved in, killing at least four people, the state news agency said.

A 250-foot-wide section of road over the construction site collapsed in the eastern city of Hangzhou on Saturday, trapping workers and creating a huge crater into which at least 11 vehicles plunged.

Poor construction quality is a chronic problem in China, and is often blamed on bad planning, shoddy work or theft of materials.

The official Xinhua News Agency said rescuers were pumping out water that had seeped into the tunnel from a nearby river and stood at 10 feet deep.

More residents of Southern California were urged to leave their homes Sunday despite calming winds that allowed a major aerial attack on wildfires that have destroyed hundreds of homes and blanketed the region in smoke.

Fires burned in Los Angeles County, to the east in Riverside and Orange counties, and to the northwest in Santa Barbara County. More than 800 houses, mobile homes and apartments were destroyed by fires that have burned areas more than 34 square miles since breaking out Thursday.

No deaths have been reported, but police brought in trained dogs Sunday morning to search the rubble of a mobile home park where nearly 500 homes were destroyed. They didn't find any bodies after searching about a third of the homes.

"This has been a very tough few days for the people of Southern California," Gov. Arnold Schwarzenegger said after touring damage.

CHENGDU, China - A powerful earthquake toppled buildings, schools and chemical plants Monday in central China, killing about 10,000 people and trapping untold numbers in mounds of concrete, steel and earth in the country's worst quake in three decades.

The 7.8-magnitude quake devastated a region of small cities and towns set amid steep hills north of Sichuan's provincial capital of Chengdu. Striking in midafternoon, it emptied office buildings across the country in Beijing and could be felt as far away as Vietnam.

As Tuesday dawned, rescuers were frantically searching for more survivors, but rain was compounding the difficulty. Premier Wen Jiabao, who flew to the region, said rain was forecast for the next several days.

The government was pouring in troops to aid in the disaster recovery. Xinhua said 16,000 were in the area and 34,000 more were en route.

The earthquake also rattled buildings in Beijing, 930 miles to the north, causing evacuations of office towers. People ran screaming into the streets in other cities, where many residents said they had never felt an earthquake.

In Beijing, where hundreds of thousands of foreign visitors are expected for the Olympics, stadiums, arenas and other venues for the games were undamaged.

"The Olympic venues were not affected by the earthquake," said Sun Weide, a spokesman for the Beijing organizing committee. "We considered earthquakes when building those venues."