The quake hit at 4:30 pm local time (1400 IST) yesterday, at a depth of 12 kms with the epicentre in Longtoushan township, 23 kms southwest of the county seat of Ludian, Zhaotong City.
At least 381 people have been killed as of this morning, state-run Xinhua news agency reported today.
The massive quake left a trail of destruction with more than 12,000 houses toppled and 30,000 damaged, it said.
Chinese Premier Li Keqiang is en route to the quake region to supervise disaster relief work, the news agency said.
Over 1,591 were injured in Ludian County and the quake has also left 60 dead and 193 injured in Qiaojia County.
This is the second quake in about two years.
In September 2012, a 5.7-magnitude quake caused more than 80 deaths and injured over 800 people.
In 1974, a 7.1-magnitude quake in the same place killed more than 1,400 people.
Jiang Haikun, a research fellow with the CENC, said that aftershocks measuring 5 to 6 on the Richter scale are possible in the area, but he ruled out the possibility of stronger quakes in the epicentre.
“Yunnan is prone to moderate and strong quakes, and such quakes usually occur on similar scales. We will keep a close eye over the aftershocks,” Jiang told Xinhua.
President Xi Jinping has ordered that authorities concerned give top priority to saving people’s lives, minimise casualties and guarantee a proper settlement for quake victims.
He called for putting an all-out effort in relief operation and strengthening aftershock monitoring to prevent secondary disasters.
Premier Li also made instructions for disaster relief, urging local authorities to try every possible means to save the injured people and those buried in rubble.
He asked local authorities to provide residents in quake zone with adequate food, clothes, clean drinking water, temporary shelters and timely medical treatment.
Local authorities have dispatched more than 7,000 rescuers to the quake zone, including troops, police officers, fire- fighters and government officials.
They were joined by more than 2,500 troops sent by the Chengdu Military Area Command of the People’s Liberation Army, and 60 medical workers and 90 rescuers sent by authorities in the neighboring Sichuan Province.
In addition, the Yunnan Branch of China Eastern Airlines has brought relief work teams to Zhaotong.
The civil affairs authorities said that 20,050 tents, 15,000 folding beds, 29,500 quilts and 25,000 coats have been sent to the area.
However, unfavorable weather conditions may hamper rescue and relief work, as it is raining hard in the quake zone.
More rains are forecast in the coming week, according to the China Meteorological Administration.