LUDIAN, Yunnan, Aug. 4 -- Blocked roads and torrential rains are hindering the relief efforts after a strong earthquake killed at least 381 people and injured 1,800 others in the mountainous southwest China.

Chinese Premier Li Keqiang is en route to the quake region to supervise the disaster relief work.

A total of 7,000 rescuers, including 5,000 soldiers, police officers, and firefighters, in the quake-prone province of Yunnan, are working to move the injured out of the disaster-hit region. They are also battling the continual downpour that has brought down the temperature in the remote area and made shortages of food and medicine even more pernicious.

Xinhua journalists in Ludian county seat, 23 km away from the epicenter and one of the worst-hit regions, saw drenched survivors sit along the muddy roads waiting for food and medication. Some half-naked survivors were quivering in the rain.

Thundershowers and downpour are expected in Ludian in the next four days when the lowest temperature could drop to 17 degrees centigrade at night.

Medics in Ludian's Longquan Village told Xinhua that they are in severe shortage of medicines and the 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 make-shift tent in the village said. "It is impossible to deal with severe injuries such as intracranial hemorrhage in such a condition."

Frequent aftershocks have ensued the 6.5-magnitude earthquake since Sunday afternoon when it first struck. Yunnan officials have called the earthquake the most powerful one to hit the quake-vulnerable province over the past 14 years.

As of 12 p.m. Sunday, over 210 aftershocks have hit the region with three of them measuring over 4 on the Richter scale.

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.

Official statistics showed that as many as 57,200 people in Zhaotong city, where the quake-hit Ludian, Qiaojia counties, Zhaoyang District and the county-level city of Qujing belong, are waiting to be relocated.

Rescuers' efforts to reach and relocate the injured are being hindered by damaged roads and the jumble of the toppled houses, some of which are built with mud and wood.

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

Liu said that they are in severe shortage of professional rescue team and facilities and it is difficult to have the roads damaged by the quake cleared.

"With the roads blocked, more relief work is hard to be carried out," Liu added.

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 in store in Zhaotong and Ludian. But the problem is how to have them delivered to the quake-hit areas.

Progresses, though slow, are also being made. Over 1,500 residents in Huodehong township have been moved to safety as a quake lake is posing threat to the region where the earthquake has killed 21 and left another 30 missing.