A military helicopter crashed while evacuating injured survivors of China’s earthquake, state media said earlier this week, underlining the lingering risks of a disaster that has killed more than 69,000.??

The chopper crashed Saturday amid fog and turbulence as its crew of four was evacuating 10 injured residents from devastated areas of south western Sichuan province, the state-run Xinhua news agency said.??No information on casualties was given.?The crash highlights the ongoing challenges China faces as it responds to a tragedy that has left about 15 million people homeless and raised fears of disease outbreaks in affected areas.

The helicopter had ferried a team of military medical experts to Li county and was returning with the injured residents when it lost contact with ground command, Xinhua reported.

The death toll from the quake, China’s worst disaster in a generation, rose to 69,016 on Sunday, with another 18,830 still missing, the government said.

Meanwhile, hundreds of thousands of Chinese waited anxiously for the start of drainage work on a menacing lake created by the May 12 quake.

Army and police crews who had toiled for a week to dig a diversion channel for the Tangjiashan "quake lake" wrapped up late Saturday. Authorities said the rising waters could begin spilling into the channel any time.

The lake, formed when a huge landslide blocked the Jian River, has emerged as the most serious lingering threat to the region’s citizens, posing flood risks to areas populated by more than one million people.

State television had said earlier that plans to use explosives to breach the lake had been abandoned amid fears the blast could destabilize the rubble.

More than 197,000 people have been evacuated in case the controlled water drainage turns into a flood, officials told AFP, and more than one million others are on standby.

Officials have expressed confidence that the risk of a disastrous flood is remote.