A strong earthquake that hit southwest China's mountainous Yunnan province has killed one person, and left more than 300 people injured as well as 50,000 displaced, state media said Wednesday.

The shallow 6.0 magnitude quake hit late Tuesday in a region that lies close to China's borders with Myanmar and Laos, the US Geological Survey (USGS) said.

One person was so far known to have died, the official Xinhua news agency said. It added that 324 people were injured, mainly in Jinggu County, close to the epicentre of the quake.

It quoted local officials as saying more than 92,000 people in Jinggu were affected and that 56,880 of them had been relocated.

"Many houses collapsed and we are investigating the casualties," a local official told the agency. "The aftershocks seem non-stopping."

Provincial officials declared a top-level emergency, with 3,200 troops dispatched in a "race to save more lives", according to Xinhua.

An additional 600 professional rescuers with sniffer dogs have been sent to the quake zone.

The epicentre was located 85 kilometres (around 50 miles) from Pu'er city, in a region famous for its tea plantations. The quake was also felt in Yunnan's provincial capital Kunming.

Xinhua gave a significantly higher reading of 6.6-magnitude, citing the China Earthquake Networks Center.

The agency said buildings shook for several seconds, while some towns in the area had lost power supply and telecommunications.

"The whole building was shaking terribly with a loud cracking sound. Plates fell off in the kitchen. We all ran out and the streets are now packed with people," Li Anqin, a woman living in Weiyuan town, the county seat of Jinggu, told Xinhua via telephone.

Thousands of homes were also damaged in the neighbouring city of Lincang, according to the news agency.

Photos on social media showed damaged houses, cracked walls and fallen roof tiles, and crowds of people gathered outside into the night.

The epicentre of the quake was in a densely-populated but underdeveloped area home to various ethnic minorities, according to Xinhua.

Yunnan is acutely vulnerable to earthquakes. The region sees frequent seismic activity from the collision of the Indian and Eurasian tectonic plates, which form the vast Himalaya mountain range.

In August, a 6.1-magnitude struck the province killing more than 600 people. More than 3,000 people were injured, while more than 80,000 homes were fully or partially destroyed.

Rescuers arriving on the scene early Wednesday said the destruction did not initially appear to be on the massive scale of the August quake.

"It's not like last time in Ludian -- there are no massive collapse of buildings. It's such a relief," rescue chief Chen Xianhe told Xinhua.

Yunnan's neighbouring Sichuan province was struck by a particularly brutal quake in 2008 in which more than 80,000 victims perished.