Rescuers worked through a steady rain as they searched 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 of homeless spent a second night outdoors, some sleeping under plastic sheeting, others bused to a stadium in the city of Mianyang, on the edge of the disaster area.
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 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."
The city of Dujiangyan was one of the worst hit areas, reports CBS News' Celia Hatton. Here, a hospital collapsed, leaving medical staff to search for anyone left alive.
Nearby, grieving parents gathered outside the ruins of a school where 1,000 students are dead or missing, Hatton reports. Not far off another school was crushed under a landslide.
"The whole mountain seemed to fall down towards us and we were all buried underneath the buildings", explained one teacher, who managed to escape from the rubble.
As night fell, a first wave of 200 troops entered the town of Wenchuan, near the epicenter, trudging across ruptured roads and mudslides, state television said. Initial reports from soldiers said one nearby town could account for only 2,300 survivors out of 9,000 people, China Central Television said.
At least 12,012 deaths occurred in Sichuan alone while another 323 died in five other provinces and the metropolis of Chongqing, state media reported. That toll seemed likely to jump sharply as rescue teams reached hard-hit towns.
The devastation and ramped-up rescue across large, heavily populated region of farms and factory towns strained local governments. Food dwindled on the shelves of the few stores that remained open. Gasoline was scarce, with long lines outside some stations and pumps marked "empty."
Buses carried survivors away from Beichuan, which was flattened - a few buildings standing amid piles of rubble in a narrow valley, according to CCTV video.
More than 10,000 people from there and surrounding areas packed Mianyang's Jiuzhou Gymnasium, with empty water bottles, boxes of instant noodles and cigarette cartons littering the ground.
"I saw rocks and earth rolling down the hill, and they destroyed whatever they hit below," said a farmer who only gave his surname, Chen, from the village of Leigu near Beichuan. "There's nothing I can do about this. It's all in the hands of the government."
In the provincial capital of Chengdu, FM-91.4 all-traffic radio station operated around the clock, reading text messages sent by survivors of stricken areas to let relatives know they are alive.
"You're looking at a city similar to New York, maybe 10 to 12 million people in the city, and literally 95 percent of them at least are living on the street because they are too scared to go back into the buildings," eyewitness Mark Laws told CBS News anchor Katie Couric from Chengdu.
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.
As Prime Minister Wen Jiabao crisscrossed the disaster area to oversee relief efforts, the official Xinhua news agency cited the Defense Ministry as saying that some 20,000 soldiers and police arrived in the disaster area, with 30,000 more on the way by plane, train, truck and on foot.
"We will save the people," Wen said through a bullhorn to survivors in Shifang, where two chemical plants collapsed and buried more than 600 people, according to CCTV. "As long as the people are there, factories can be built into even better ones, and so can the towns and counties."
The Finance Ministry said it had allocated $123 million in quake aid.
At the world famous Wolong National Nature Reserve,late Tuesday in the first word since communications with the preserve were cut off. A group of 31 British tourists panda-watching in the preserve also returned safely to Chengdu, the Foreign Ministry said, although there was no word on 12 missing Americans on a World Wildlife Fund tour.
Still, prospects for survivors in the quake zone dwindled. Only 58 people were pulled from demolished buildings across the quake area so far, China Seismological Bureau spokesman Zhang Hongwei told Xinhua.
Weeping parents held a vigil in a steady outside a collapsed school in the town of Juyuan, where more than 900 high school students were initially trapped. Only one survivor has been found: a girl pulled free by rescue team.
Bowing to public calls, Beijing Olympics organizers scaled down the boisterous ongoing torch relay, saying Wednesday's leg in the southeastern city of Ruijin will begin with a minute of silence and more somber ceremonies. People along the route, which next month is scheduled to arrive in quake-hit areas, would be asked for donations, an organizing committee spokesman said.
In the areas around Mianyang, more than 7,300 people died and another 18,000 were believed trapped in rubble, most in Beichuan. Amid the rubble, CCTV showed the six-story Beichuan Hotel listing, half its first story collapsed. Medical teams tried to treat the wounded in dirt courtyards littered with broken furniture and concrete.
Though Wen and others called for air drops of emergency supplies to hard-to-reach areas, rain impeded efforts for a second day, and Xinhua said a group of paratroopers called off a rescue mission.
Strong aftershocks - one of magnitude-6, according to Chinese seismologists - hit Chengdu, the region's usually busy commercial center. A KFC outlet ran out of chicken and cooking oil.
Expressions of sympathy and offers of help poured in from Japan and the European Union. Russia was sending a plane with 30 tons of relief supplies, the Interfax news agency said. Chinese President Hu Jintao discussed the disaster by phone with President Bush.
The U.S. is offering an initial $500,000 in relief in anticipation of an appeal by the International Red Cross, White House spokeswoman Dana Perino said.
While welcoming the support, the Chinese government suggested that aid would be confined to supplies and money, not foreign personnel.
"We welcome funds and supplies. We can't accommodate personnel at this point," Wang Zhenyao, the Civil Affairs Ministry's top disaster relief official, told reporters in Beijing.
The Dalai Lama, who has been vilified by Chinese authorities who blame him for recent unrest in Tibet, offered prayers for the victims. The epicenter skirts the Tibetan highlands, where some communities staged anti-government protests in March.
Seismologists said the quake was on a level the region sees once every 50 to 100 years. The region's last strong quake was in 1933, when a magnitude 7.5 quake killed more than 9,300 people. Monday's quake was powered up the pent-up stress, experts said.