The overall death toll increased to about 10,000, the official Xinhua News Agency reported Tuesday. It said nearly 10,000 people died in central China's Sichuan province alone and 300 others in three other provinces and the mega-city of Chongqing.

Worst affected were four counties including the quake's epicenter in Wenchuan, 60 miles northwest of Chengdu. Landslides left roads impassable Tuesday, causing the government to order soldiers into the area on foot, state television said, and heavy rain prevented four military helicopters from landing.

Wenchuan's Communist Party secretary appealed for air drops of tents, food and medicine. "We also need medical workers to save the injured people here," Xinhua quoted Wang Bin as telling other officials who reached him by phone.

To the east, in Beichuan county, 80 percent of the buildings fell, and 10,000 people were injured, aside from 3,000 to 5,000 dead, Xinhua said. State media said two chemical plants in an industrial zone of the city of Shifang collapsed, spilling more than 80 tons of toxic liquid ammonia. The news agency said about 600 people died in Shifang and up to 2,300 were buried by rubble.

Though slow to release information at first, the government and its state media ramped up quickly.

Wen, a geologist by training, held an early morning emergency meeting near Chengdu and ordered troops and police to clear the road north to Wenchuan.

"We must try our best to open up roads to the epicenter and rescue people trapped in disaster-hit areas," he said. Wen said the earthquake "was more serious" than expected.

Television footage showed large boulders and downed trees blocking the road to Wenchuan.

Disasters always pose a test for the communist government, whose mandate rests heavily on maintaining order, delivering economic growth, and providing relief in emergencies.

Pressure for a rapid response was particularly intense this year, with the government already grappling with public discontent over high inflation and a widespread uprising among Tibetans in western China while trying to prepare for the Aug. 8-24 Beijing Olympics.

"I am particularly saddened by the number of students and children affected by this tragedy," President Bush said in a statement.

U.S. State Department spokesman Sean McCormack said no aid requests had been made by China.

International Olympic Committee President Jacques Rogge sent his condolences to President Hu Jintao, adding: "The Olympic Movement is at your side, especially during these difficult moments. Our thoughts are with you."

The quake was the deadliest since one in 1976 in the city of Tangshan near Beijing that killed 240,000 — although some reports say as many as 655,000 perished — the most devastating in modern history. A 1933 quake near where Monday's struck killed at least 9,000, according to geologists.

Monday's quake occurred on a fault where South Asia pushes against the Eurasian land mass, smashing the Sichuan plain into mountains leading to the Tibetan highlands — near communities that held sometimes violent protests of Chinese rule in mid-March.