As rescuers continue to look through the rubble left by a 6.5 magnitude earthquake that struck southwestern China’s Yunnan province on Saturday, heavy rain and landslides are slowing down rescue efforts with even worse weather to come.

Thunderstorms and torrential downpours are forecast over the next three days for Ludian County, one of the worst affected areas, forcing thousands of troops, police and other aid workers to race against time.

The quake struck an area of steep hills and narrow roads, and heavy rain on Tuesday added to the complications. Much of the damage was due to landslides.

The Yunnan Civil Affairs Bureau said on Tuesday that more than 400 people had been killed and more than 2,200 injured. Twelve people were still missing about 36 hours after the quake.

Rescuers pulled dozens of trapped people from the debris in the first couple of days.

Many of the homes in Ludian, which has a population of about 429,000, were rudimentary mud-brick structures that collapsed easily in the quake.

Further from the worst-hit areas, landslides had created barrier lakes where water levels were rising on Tuesday, posing a new threat to about 800 residents and seven power stations downstream, where sudden flooding could prompt power cuts. Xinhua News Agency reported.

More coverage on Yunnan earthquake.

Report compiled from information for Xinhua and The Associated Press.