Residents listen for sounds of life in the rubble of a collapsed building in Dujiangyan, in southwestern China's Sichuan Province. Thousands of people are believed buried in the debris of collapsed buildings.

Mianyang, China ? Soldiers hiking over landslide-blocked roads reached the epicenter of China’s devastating earthquake Tuesday, pulling bodies and a few survivors from collapsed buildings. The death toll of more than 12,000 was certain to rise as the buried were found.

As many as 18,000 were believed buried under debris in the area surrounding the city of Mianyang, near Chengdu in Sichuan province.

Rescuers worked through a steady rain searching wrecked towns across hilly stretches of Sichuan province that were stricken by Monday’s magnitude-7.9 quake, China’s deadliest in three decades. Tens of thousands spent a second night outdoors, some sleeping under plastic sheeting, others bused to a stadium in Mianyang, on the edge of the disaster area.

As night fell, a first wave of 200 soldiers entered the town of Wenchuan, near the epicenter, trudging across ruptured roads and mudslides, state television said.

Soldiers continued their efforts this morning, and Xinhua said another 800 armed police arrived.

Helicopters were preparing to fly in relief supplies if the weather permitted to areas not accessible by roads.

Street lamps were switched on in Mianyang on Tuesday night, but all the buildings were dark and deserted after the government ordered people out of them for fear of aftershocks. Security guards were posted at apartment blocks to keep people out.

The industrial city of 700,000 people – home to the headquarters of China’s nuclear weapons design industry – was turned into a thronging refugee camp, with residents sleeping outdoors.

“I’m cold. I don’t dare to sleep, and I’m worried a building is going to fall down on me,” said Tang Ling, a 20-year-old waitress wrapped in a borrowed pink down jacket and camped outside the Juyuan restaurant with three co-workers. “What’s happened is so cruel. In one minute to have so many people die is too tragic.”

State television today broadcast touching scenes of Premier Wen Jiabao at the Mianyang stadium comforting children whose parents were killed in the earthquake.

“The government will take care of you.” Wen told a girl about 9. “Since you survived, you must live your life well.” The child cried and covered her face.

The government’s high-gear response aimed to reassure Chinese while showing the world it was capable of handling the disaster and was ready for the Aug. 8-24 Olympics in Beijing. Although the government said it welcomed outside aid, officials said that the assistance would be confined to money and supplies, not to foreign personnel.