- NEW: At least 80 killed as death toll climbs
- The quakes hit near the border of Yunnan and Guizhou provinces
- Their magnitudes range between 4.8 and 5.6, the U.S. Geological Survey says
- More than 430,000 houses are damaged and 6,600 destroyed, a state media report says
Beijing (CNN) -- A series of earthquakes in southwestern China Friday killed at least 80 people and injured 731, the state-run Xinhua news agency reported.
More than 6,600 homes were destroyed and about 430,000 damaged, according to Xinhua.
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Premier Wen Jiabao was on his way to the scene, the news agency reported. President Hu Jintao called for immediate relief efforts, according to China Central Television.
Xinhua reported that 100,000 people have been evacuated and another 100,000 are in need of relocation.
Initial estimates put the "direct economic losses" at more than half a billion dollars, the news agency said.
The four quakes struck near the border of the provinces of Yunnan and Guizhou between 11:19 a.m. and 1:12 p.m. local time, the U.S. Geological Survey said. Their magnitudes ranged between 4.8 and 5.6, it said.
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The first quake took place at the area of the border between Yiliang County in Yunnan and Weining County in Guizhou, Xinhua said. The news agency cited unidentified government sources for the death toll and damage figures.
All four quakes hit at a depth of about 10 kilometers (six miles), the USGS said.
The southwestern region of China is prone to earthquakes. In May 2008, a magnitude 7.9 quake in Sichuan province caused widespread devastation, killing at least 69,000 people.
CNN's Steven Jiang contributed to this report.
