Zhou Chun told The Associated Press, "My wife died in the quake. My house was destroyed." He walked out of Dujiangyan with a wet blue blanket draped over his shoulders. "I am going to Chengdu," he said, "but I don't know where I'll live."
In Wenchuan, the local communist party secretary told Xinhua that at least 30,000 of the county's 105,000 residents slept outside Monday night.
In Beichuan county, 30 miles away, 80 percent of the buildings fell and 10,000 people were injured.
"People were just outside running around, crying, there were people running around, blood coming off of them," Heather Rauch, a junior at Texas A&M who was visiting Changdu, told ABC's "Good Morning America."
"You could look up at buildings and there were giant cracks running from the bottom all the way to the top of the buildings," she said.
She walked to a hospital that was being evacuated.
"We saw people who looked like they were on their death bed and they were being carried out," she said. "You looked at these people's faces and you just knew they had no idea what had just happened."
Lucy Jones, chief scientist for the Multi Hazards Demonstration Project at the U.S. Geological Survey, said the earthquake happened on the Longmenshan Fault, which is pushing the Tibetan Highlands up and over the Sichuan Basin.
"This fault was recognized as one of [the] dangerous faults of China," Jones told "GMA."
"Given the size and the location of this earthquake, we've only touched [the] surface of damage in Sichuan," she said.
Jones said a quake of this magnitude will instantly turn a brick building into a rubble.
"When you shake brick, the mortar in between dissolves. The building comes down and the roof kills people. They're some of the most deadly buildings in the world," she said.
A magnitude 7.9 quake can turn ground with a sandy base into quicksand, toppling buildings sideways as if they were bobbing on water, a phenomenon known as liquefaction, Jones said.
From what she knew of the area, "It's probably going to be sandy and probably subject to liquefaction."
China has launched a massive and unprecedented aid effort. In Mianyang, all able-bodied males younger than 50 years old were ordered to take water and tools and walk or drive to Beichuan. The government announced a national drive for blood donors. State airlines were asked to transport aid. And the Red Cross society of China called for donations. The government says it welcomes aid but is not allowing foreign relief workers into the area around the epicenter.
"Not one minute can be wasted," the Chinese prime minister, a geologist by training, said. "One minute, one second could mean a child's life."
But not everyone in need has been reached, and hope in pulling bodies out of the rubble is decreasing. Only 58 people have been extracted out of buildings, Xinhua reported.
"Time is of the essence," Wang Zhenyao, the disaster relief division director at the Ministry of Civil Affairs, told reporters in Beijing. Rescue efforts, he said, could take up to a week. "Survivors can hold on for some time. Now it's not time to give up."
With the Olympics now only three months away, officials are aware that failure to deal humanely and efficiently with this quake will be a public relations disaster. They are also anxious to avoid the reputation of bureaucratic indifference that has marked Myanmar's cyclone relief efforts.