LUDIAN, Yunnan, Aug. 4 -- Rescuers are racing against time to save lives after a 6.5-magnitude earthquake killed at least 381 people and injured 1,800 others in southwest China's Yunnan Province.

Yunnan has sent 7,000 rescuers, including 5,000 soldiers, police officers and firefighters, to the quake-hit areas in Zhaotong City and Qujing City.

The rescue work has been hampered by continuous downpours, which have disrupted traffic, lowered temperatures in the remote area, and made food and medicine shortages even more dangerous.

Thundershowers and downpours are expected in Ludian County, one of the most worst-hit regions, over the next four days, and temperatures could drop to 17 degrees centigrade at night.

Premier Li Keqiang has flied to the quake-struck area to direct rescue work.

The quake has led to evacuation of 29,400 people in Zhaotong as of 8 a.m. Monday, said a government spokesman at a news conference. It has affected over 980,000 people in the city, with more than 11,400 houses collapsed and 24,000 damaged, said the spokesman.

Rescuers are evacuating residents threatened by a quake lake, which was formed in Jiangbian Village, Zhixiang Township of Huize County and has inundated 20 village houses.

The water level of the lake is surging rapidly at a speed of one meter per hour. The lake was formed following a landslide that occurred in the upper reaches of the Hongshiyan hydropower station, which is under construction.

Xinhua journalists in Ludian county seat saw drenched survivors sitting along the muddy roads waiting for food and medication. Some half-naked survivors were trembling in the rain.

Medics in Ludian's Longquan Village told Xinhua that they have severe shortages of medicine and local conditions are too poor to perform operations for the severely injured.

"The critically injured patients keep coming, but we are unable to carry out operations for many of them," one of the doctors working at a makeshift tent in the village said. "It is impossible to deal with severe injuries such as intracranial hemorrhage in such conditions."

Frequent aftershocks have followed the earthquake since it first struck on Sunday afternoon. Yunnan officials have called the earthquake the most powerful to hit the quake-vulnerable province in the past 14 years.

China Earthquake Administration said as of 8 a.m. Monday, 411 aftershocks had been recorded in the quake-hit region, with four measured between 4.0 to 4.9 magnitude and five between 3.0 to 3.9 magnitude.

Local seismic experts have warned that aftershocks measuring 5 to 6 on the Richter scale are possible in the area, but ruled out the possibility of stronger quakes in the epicenter.

Earlier official statistics showed that as many as 57,200 people in Zhaotong are waiting to be evacuated.

"The blocked roads and the continuous downpours have made some disaster areas inaccessible for heavy relief vehicles," said Liu Jianhua, Secretary of the Communist Party of China Zhaotong Municipal Committee.

Liu said that they are experiencing a severe shortage of professional rescue teams and facilities. "With the roads blocked, it is difficult to carry out more relief work," Liu added.

Traffic on a life line linking the epicenter of Longtoushan township, Ludian County and the county seat became smooth Monday morning after hours of gridlock after the quake. Via the road, large numbers of the injured are being transfered by ambulances to the county's hospital.

Officials with the Yunnan Provincial Department of Civil Affairs told Xinhua that a large number of tents, cotton quilts and fold-out beds had been stored in Zhaotong and Ludian, but there have been problems having them delivered to the quake-hit areas.

The 11th Panchen Lama, Bainqen Erdini Qoigyijabu, told Xinhua that he was grieving over the quake and prayed for the living to avoid suffering and the deceased to receive early relief.