Beijing, Aug 8 (IANS): Over 80 people were killed and 2,000 went missing Sunday morning after landslides triggered by torrential rains hit northwest China's Gansu province, an official said.

The landslides occurred at around 12 a.m. Sunday in Zhouqu county in Gannan Tibetan Autonomous Prefecture. More than 80 people have been confirmed dead and some 2,000 others are missing, said Mao Shengwu, an official.

"Torrential rains began at around 10 p.m. Saturday, then there were landslides," Xinhua quoted Diemujiangteng, head of the county, as saying.

"Many people were trapped. Now the sludge has become the biggest problem. It's too thick to walk or drive through," he said.

At least 50,000 residents in the county seat and nearby regions were believed to be affected as floods had submerged half of the county and many houses were buried by landslides, authorities said.

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

Peng Wei, head of the county's fire department said: "The county was in a valley and the Bailong River runs in the middle...The cars in the yard have all been damaged. Many toppled houses have formed new barriers to the floods.

A barrier lake was formed on the Bailong River which runs through the county at around 1 a.m.

Two helicopters carrying demolition experts left for the landslide-hit county at 6.30 a.m. Sunday to explode the barrier lake, according to the provincial flood relief headquarters.