The orange-suited emergency workers had just pulled someone out of the rubble alive Saturday when a chilling cry reverberated around the tilting high-rises, the toppled construction cranes and the market littered with bodies: The valley was about to flood.
In a panic, thousands of soldiers, earthquake survivors and aid workers raced headlong for the hills, some helping babies and the elderly negotiate a mountain of jagged debris. "Move it!" yelled one commander. "Don't worry about your equipment -- just get to higher ground," barked another.
Authorities issued the warning to evacuate Beichuan, fearing that water from a choked river might overrun this obliterated town near the epicenter of Monday's magnitude 7.9 quake. The official New China News Agency reported that a lake created by quake-triggered landslides "may burst its banks at any time."
"I don't want to die," one survivor cried out, kneeling in terror on a rubble pile, his head repeatedly touching the ground in prayer.
The government in Beijing has been playing down the threat of another disaster as it works overtime to reassure the public. But the warning Saturday underscored how jittery people's nerves still were, given aftershocks and the deadly risk that flooding in this mountainous area could pose.
The confirmed death toll Saturday rose to 28,881, Cabinet spokesman Guo Weimin said, with 10,600 people still reportedly missing in Sichuan.
Every so often, despite the odds, a survivor is found in the wreckage. The New China News Agency said early today that a man was found alive after being trapped for 139 hours -- more than five days -- in a collapsed hospital in Beichuan. Tang Xiong "was only slightly bruised," the agency said.
Two U.S. Air Force cargo planes were expected to arrive in Sichuan today from Hawaii and Alaska with tents, blankets, food and generators, the first aid flights from the U.S.
Hardly a building has been left untouched in Beichuan, which sits in a valley with steep mountains on both sides. All the police stations and prisons were destroyed; all six of the city's deputy mayors are missing or dead; and most of its 30,000 residents appear to have been buried or have fled.
Ten-story buildings teeter at odd angles, some supported by the debris from adjacent buildings, while a five-square-block area in the center of town is a massive field of rubble that has buried streets and other landmarks.
"I can't recognize any street," said Ma Zizhang, 60, looking for his missing younger brother Ma Ziyuan. "I was born here and have lived here for decades, but none of this makes sense. What's happened is madness."
A team of 15 emergency workers, part of a bigger group that flew in from the eastern province of Jiangxi, had spent two days fanned out amid the debris looking for survivors. Most members carried ropes, shovels and picks, with one wielding a life-detection device, essentially a 5-foot pole with a cable equipped with a microphone and video camera.
The team moved along, with members banging on debris with hammers or shovels and yelling, "Anyone in there?" "Can you hear me?" and listening for a response. On two occasions Saturday, the rescuers got excited when they heard cellphones ring from inside the rubble, only to conclude that the owners must be dead.
The crew had a victory shortly after noon when a person gave them the approximate location where a relative might be. They found the building and lowered the cable into a crevice. Emergency worker Ye Bin, who was operating the device, said he heard a faint voice in response to their calls. For 2 1/2 hours, the crew worked by hand to free the man.
The victim, underground nearly five days, had been on the second floor of a six-story building when the quake struck. Somehow he managed to land face down in an 18-inch space between collapsed floors. When the rescuers finally freed him, they whisked him to an ambulance to a hospital before returning to their search.
"He came out very strong, immediately asked about his family and had us call their cellphone," said Pan Yonghong, commander of the disaster relief team. "As every day passes, the chances of finding survivors are reduced. But if there's a 1% chance, we'll continue to exert 100% effort."
As the afternoon wore on, the crew hoped for a second miracle, passing through a wrecked shopping area, shooing a flock of chickens that was scrounging around five bloated bodies, before starting their climb onto the debris field.
After several arduous minutes navigating an obstacle course of spiky timbers, near-vertical slabs of concrete and steel rods, the group found a promising spot on a foothill of rubble about 60 feet above what would have been street level, and resumed their calls of "Anyone there?"
Then, about 3 o'clock, Pan got a phone call about the flood warning. The group scrambled at full speed about 150 feet up to the top of the debris, wary that a large chunk could collapse and bury them.
A giant downed crane and hundreds of concrete forms suggested that the summit was the top floor of a skyscraper that had been under construction when the quake hit.
The top of the heap afforded a panoramic view of the damage that nature could deal out in a few short minutes. As confusion and panic spread, two military helicopters headed up the valley in the direction of the blocked water.
There was uncertainty over the source for the scare. There had been reports in recent days that the quake might have weakened dams in the area. But officials indicated that the problem was a so-called barrier lake, created when a quake or avalanche dams a river.
"This earthquake struck places where there is quite a lot of water conservancy and reservoirs," Chinese Agriculture Vice Minister Wei Chao'an told reporters Saturday. "Some reservoirs and water-control projects have had some damage."
Dai Ping, a Chinese environmental activist, said the government had underplayed the risk of flooding.
"A lot of this is top-secret. They don't want to talk about it," Dai said. "After earthquakes, new lakes are formed and they are very dangerous because they are unstable."
Times staff writer Barbara Demick in Beijing and Gao Wenhuan of The Times' Beijing Bureau reporting from Beichuan contributed to this report.