LUDIAN, Yunnan - Rescuers are risking their lives as they work to open roads and defuse the threat of barrier lakes in mountainous areas of southwest China's Yunnan province Tuesday after a devastating earthquake.

Key Points A 6.5-magnitude earthquake rattled southwest China's Yunnan province at 4:30 p.m. Sunday. The epicenter is in Longtoushan Township, 23 km southwest of the county seat of Ludian, in Zhaotong city. More than 12,000 houses have been toppled and 30,000 damaged in the quake zone. At least 410 people dead and 1,801 injured Many of the homes that collapsed in Ludian, which has a population of about 429,000, were old and made of brick.

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Landslides have blocked roads leading to Longtoushan Township in Ludian County, epicenter of Sunday's tremor, which killed at least 410 people and injured more than 2,300 others.

A road leading to a large barrier lake on Niulan River was made passable after 38 hours of repairs by an armed police squad. Repair work is underway on three other roads in the quake zone.

As of 6 p.m. Tuesday, accumulated water volume of the barrier lake had reached 49.6 million cubic meters, and the water level is increasing at a speed of 16 cm per hour, said Sun Huaikun, a technical specialist in charge of the barrier lake response.

Sun told a press conference late Tuesday that 4,200 residents living on the lower reaches of the Niulan River had been evacuated. A reservoir, located on the upper reaches, is required to intercept river water and reduce pressure on the barrier lake.

Barrier lakes, formed by landslides blocking rivers, are a recurrent threat to the lives of victims and rescuers alike. A 24-year-old border policeman is missing after he was hit by a falling rock as he attempted to swim a barrier lake in search of survivors.

More than 60 soldiers were trapped by a sudden flood from a barrier lake Tuesday afternoon and were rescued by another team of armed police.

The quake also damaged reservoirs and water pipes, cutting off supplies for over 300,000 people. Currently, local bottled water plants are providing 50 tonnes of drinking water every day.

"As traffic has improved, we delivered 20 tonnes of bottled water and we are repairing water pipes as quickly as we can," said Zhou Minghui, head of Ludian water bureau.

Rescue continues

Rescuers are still racing against time to save lives as the death toll rises. More fatalities may still be reported as the rescue work spreads to remote locations.

In a "miracle" rescue, an 88-year-old woman was pulled from a pile of rubble in the Babao Village late Tuesday after being buried for more than 50 hours.

She is unhurt and her health is fine, rescuers and doctors said.

At midday Tuesday, rescuers dug the body of a ten-year-old girl out of a collapsed house in Longtoushan.

"We have detected 12 people buried beneath the rubble, but unfortunately there are no signs of life," said Zhang Wukuan with a special rescue team. "Four bodies have been recovered."

In Tangjiawan, Longtoushan, villagers carried the bodies of six dead residents 10 km out of the mountains on makeshift stretchers.

"Our medicine is running out and more injured people are still being sent to us," said Chen Wangchang, head of Ludian Traditional Chinese Medicine Hospital.

Relief goods such as food and tents were airlifted to several villages in Longtoushan Tuesday. Traffic controls are in place of the main road between Ludian's county seat and Longtoushan, prioritizing ambulances and vehicles carrying relief goods.

Saved by seconds

Workers are repairing roads but their efforts have been hindered by continuous downpours, falling rocks and aftershocks.

On one major road linking Zhaotong and Qiaojia, workers are removing 25 million cubic meters of debris.

Electricity supplies have resumed for three quarters of more than 38,000 households in Zhaotong and communications have mostly been restored, according to the local grid company and telecom operators.

The disaster has also damaged many small reservoirs near the epicenter. Workers have begun emptying two cracked reservoirs.

The quake, the strongest in 14 years, struck at 4:30 p.m. Sunday (Beijing Time) with its epicenter in Longtoushan Township, Ludian County in Zhaotong City, affecting 1.08 million people in the cities of Zhaotong and Qujing.

Nearly 80,000 homes collapsed and 124,000 were seriously damaged.