Rescuers convey an injured villager at quake-hit Longquan Village of Longtoushan Town in Ludian County, southwest China's Yunnan Province, Aug. 4, 2014. At least 381 people have been killed after a 6.5-magnitude earthquake rattled the province Sunday afternoon. (Xinhua/Wu Zhangjun)

BEIJING, Aug. 4 -- The National Committee for Disaster Reduction has issued the highest-level national disaster relief response to cope with an earthquake in southwest China that has killed at least 381 people.

The committee decided to lift the level of the disaster relief response from grade III to I at 11 a.m. Monday. Grade I is usually issued for "especially major natural disasters" in which more than 200 people are killed or more than 1 million people are relocated.

The committee requested further support for the quake relief work in Ludian County of Yunnan Province, the epicenter of a 6.5-magnitude earthquake Sunday.

The quake occurred at 4:30 p.m. Sunday (Beijing Time) with a depth of 12 km. The epicenter was located at Longtoushan Township, 23 km southwest of the county seat of Ludian.

The Ministry of Civil Affairs blamed poor housing structure and dense population at the epicenter for heavy casualties.

Most residences in the quake-hit zone are wood and earth structures. In the region hit hardest by the quake, about 90 percent of wood and earth and brick houses were collapsed or damaged, according to the ministry.

According to meteorological authorities, thundershowers are expected from Monday to Wednesday, adding difficulty to relief work in the mountainous region.

As of 10 a.m. Monday, 381 people were killed and another three went missing in the quake. About 1.09 million people have been affected by the quake, with 1,800 wounded and about 230,000 relocated, according to the provincial civil affairs authorities of Yunnan.