WITNESS ACCOUNTS, BARRIER LAKE

Peng Wei, head of the county's fire department said, "I heard the fierce storm around 11:30 p.m. last night, and later I found that a mud-rock flow had hit our residential building. The cars in the yard had all been damaged," Peng added.

"Someone said the fifth floor of my residential building had been submerged. People are busy looking for family members and friends," said Li Tiankui, a resident who lived near the Bailong River.

"Several small landslides have occurred in the valley before, but they didn't arouse much attention," Li said.

Water spewed out the sides of the Bailong River due to debris blocking it and took a different downstream course than usual, engulfing buildings along the riverbank. A total of 19,000 people living in Shawan and Lianghekou townships situated below the lake had been evacuated, Mao said.

The mudslides occurred at around midnight in Zhouqu County, when the residents were asleep, and a clogged lake formed on the Bailong River at around 1 a.m.

The barrier lake is 2.6 km long, containing 2 million cubic meters of water, according to the provincial flood control department.

Two helicopters carrying demolition experts left for the landslide-hit county at 6:30 a.m. Sunday to blow up materials blocking the river's flow, according to the provincial flood relief headquarters.

Zhouqu County covers 3,010 square km and has a population of 134,700, about 33 percent of which are Tibetans. It is located in the southeast part of the prefecture, the seat of which is about 276 km away from Lanzhou, the capital of Gansu.