JIULING, China - A military helicopter carrying 10 people injured in China’s devastating earthquake and four crew members crashed in fog and turbulence, and authorities were searching for survivors, state media reported Sunday.

The Russian-designed Mi-171 transport helicopter crashed Saturday afternoon in Wenchuan county in China’s southwest, the official Xinhua News Agency reported.

There was no immediate word on any survivors or casualties. Xinhua said a search and rescue operation was under way.

The confirmed death toll from the May 12 earthquake, China’s worst in three decades, was nearly 69,000, with another 18,000 still missing.

Two injured miners who had been stranded in Sichuan province’s mountains since the quake were airlifted out Sunday in a helicopter, Xinhua said.

Six parachuting soldiers found the men a day earlier and treated them, Xinhua said.

Meanwhile, troops equipped with diggers and backhoes finished digging a channel to siphon off water from an earthquake-formed lake that authorities feared could burst and further devastate stricken areas.

The lake formed above Beichuan town in Sichuan province when a hillside plunged into a river valley during the May 12 quake. It is the largest of more than 30 quake-formed lakes.

More than 600 troops from China’s armed police force, who had been working around the clock for six days, finished digging the trench Saturday evening, Xinhua said. The channel _ nearly 500 yards long and up to 10 yards wide _ is meant to drain off some of the lake as its water level continues to rise, Xinhua said.

As a precaution, authorities evacuated about 200,000 people.

Downstream, people packed their belongings and left the villages of Jiuling and Qinglian on Sunday. Soldiers in camouflage fatigues and orange life vests patrolled the empty streets. Warnings spray-painted in red on one building in Qinglian showed how high waters might reach should the lake burst.

The quake was especially painful to many Chinese because it killed so many children _ many of whom had no siblings because of the government’s population-control policy that limits many families to one child.

Citing Sichuan’s head of family planning, Xinhua on Saturday reported that an estimated 7,000 children without siblings died and another 16,000 were injured.

The destruction of almost 7,000 classrooms has led to complaints from angry parents that schools were poorly built.

In the town of Juyuan, about 100 parents marked International Children’s Day on Sunday by gathering to mourn their children killed when a middle school collapsed. The parents also vented their anger at school and local officials.

On a large white banner hanging on a part of the school that still stands, someone had written that “a blood debt” should be paid by those responsible for allegedly shoddy construction.

One parent circulated a letter that thanked the Communist Party and government for their help but also said parents were suing school leaders and local education authorities.

To reporters taking photos, one parent yelled: “The next time you go to a news conference, ask a lot of questions. Help us get justice for our dead babies!”

China’s Cabinet has ordered appraisals of all school buildings in the quake zone, according to Xinhua. It quoted a Construction Ministry investigator, Chen Baosheng, as saying that steel concrete-reinforcement rods in the Juyuan Middle School _ where 900 students were buried _ “were too thin.”

Chen Huaqun said her 15-year-old son died in the school.