BEIJING, Aug. 4 -- The severe damage and death toll caused by Sunday's earthquake in southwest China's Yunnan Province have been blamed by Chinese authorities on the fragility of local buildings, the area's dense population and the quake's shallow epicenter.

The 6.5-magnitude quake struck at 4:30 p.m. Sunday (Beijing Time) with a depth of 12 km. The epicenter was in Longtoushan Township, 23 km southwest of the county seat of Ludian. The latest death toll stands at 398.

"Most rural houses in the county were made of brick or wood, were not designed to be resistant to quakes, and many of them were outdated," said the China Earthquake Administration in a statement.

Ludian is recognized as especially poor by the Chinese government, which includes the county seat on its state-level poverty list.

Each square kilometer of Ludian houses an average of 265 people, twice the provincial average, according to official figures.

In addition, the shallowness of the quake meant it fiercely shook the earth's surface, adding to the likelihood of secondary disasters such as landslides in the cragged area's current rainy season, the statement added.