Villagers send an SOS signal in the field of Yuli County, Sichuan Province on May 28.

More than 600 rescuers worked through heavy rain on Thursday to dig a diversion channel on one of the most dangerous lakes in China's quake-hit Sichuan Province.

Soldiers and water resources professionals worked non-stop around the Tangjiashan "quake lake" despite heavy downpours that started about 10 PM on Wednesday.

Helicopters that carried fuel, food and building equipment to Tangjiashan were grounded at a nearby town before the rain stopped around midday on Thursday.

In neighboring Mianyang City, more than 100,000 people were evacuated and are staying in tents midway up the hills or on other higher grounds. Officials have projected about 158,000 people will have to move if the lake bursts its banks.

Most evacuees are staying in tents midway up the hills or on other higher grounds. Officials have projected about 158,000 people will have to move if the lake bursts its banks.

Mianyang City has a population of about 5 million people and the residents who are threatened by flood risk have been put through evacuation drills in the last few days.

Paramilitary police officers open a road connecting Beichuan and the swollen Tangjiashan quake lake in Sichuan province on Thursday, May 29, 2008. [Photo: Xinhua]

The quake lake was formed after the May 12 earthquake as rocks and mud blocked a river. By 4 p.m. on Thursday, the water level was 745.5 meters at its highest point before the debris blockage. A total of 46 engineering vehicles, including excavators and bulldozers, have been airlifted to Tangjiashan. Currently, more than 70,000 cubic meters of rock and mud have been removed, said Liu Ning, the Ministry of Water Resources (MWR) chief engineer.

A total of 46 engineering vehicles, including excavators and bulldozers, have been airlifted to Tangjiashan. Currently, more than 70,000 cubic meters of rock and mud have been removed, said Liu Ning, the Ministry of Water Resources (MWR) chief engineer.

Soldiers also cleared an emergency retreat path on Thursday in case the water rises quickly, Liu said.

Helicopters, flying at intervals of less than 10 minutes, brought 30 tons of gasoline for the machinery. About 1,000 soldiers were on standby in a nearby town to carry the fuel to Tangjiashan if the rain hampers flights again.

The powerful earthquake has left 68,516 dead as of midday Thursday, and 19,350 others were missing, according to the Information Office of the State Council.

In the wake of the earthquake, landslides created 34 quake lakes in Sichuan alone, with 28 at risk of rupturing.