Rescuers are racing against time in the search for survivors in a mudslide-flattened northwest China county and to demolish a dam of debris to prevent further devastation from flood waters.

Personnel from the Lanzhou Area Command of the People's Liberation Army used explosives to blast a blockage in the Bailong River at 8:18 a.m., a spokesman with the emergency rescue headquarters said.

Armed police officers were then able to demolish the barrier with excavators, allowing water from a lake in Zhouqu County, Gannan Tibetan Autonomous Prefecture in Gansu Province, to drain at 95 cubic meters per second, he said.

More explosions were carried out at 9:34 a.m. and at 10:20 a.m..

A massive mudslide swept through county early Sunday, killing at least 127 people and injuring 88.

An estimated 1,294 people are missing.

Torrential rain late Sunday night sent massive waves and an avalanche of sludge and debris crashing down on the county, ripping houses from their foundations and tearing six-story apartment buildings in half.

About 1.8 million cubic meters of mud and debris flattened three villages that covered around 2.5 million square meters, about a third of the county.

Zhouqu County, about 650 km from the provincial capital Lanzhou, sits in the Bailong River valley and is hemmed in by craggy mountains on both sides.

In the worst-hit Yueyuan Village, not a single structure remained intact after the mudslide. "Hundreds of families were buried or washed away," a villager said. "The casualties and number of missing may still go up."

An air of desperation overshadowed the village Monday, as survivors and PLA officers continued searching the debris, using spades, hoes or just their hands.

Of the 88 injured, more than 70 are being treated at Zhouqu People's Hospital. At least 30 critically ill people are in intensive care.

The hospital itself is short of medical workers as more than 10 doctors are missing in the mudslide. "They are all from the worst-hit areas and they might have died too," a doctor said on condition of anonymity.

At a meeting early Monday at the emergency rescue headquarters, Health Minister Chen Zhu said a team of counselors were on their way to Quzhou, as the survivors were in urgent need of counseling.

Geologists with the Ministry of Land and Resources have blamed the county's geological structure for the mudslide, saying its loose, seriously weathered topography is prone to landslides and other disasters.

The massive earthquake of 2008 that shook the mountains around Zhouqu worsened the situation.

The geologists also pointed to sustained drought and soil erosion in the region since last winter, though the immediate cause of the tragedy was torrential rain that lasted more than 40 minutes and deposited at least 90 mm Sunday night.