SHIJIAZHUANG, Nov. 11 -- The death of a boy who fell into an abandoned well in northern China has sparked public concerns across the country.

The boy, surnamed Zhao, was found dead on Thursday night in Lixian County, Hebei's Baoding City, after search and rescue teams had been looking for him for over 100 hours, according to Wu Sujie, Lixian's vice county head.

The boy, 6, fell down the 80-meter-deep dry well on Sunday morning when helping harvest vegetables with his father, rescuers said.

The accident generated attention home and abroad, after the boy's father put out a call for help on social media platform Wechat.

"May the boy be found and safe," said a Facebook comment by Stanley Lim from Malaysia as rescue efforts were ongoing.

It took so long to find the boy, the public raised questions about the rescue efforts, while others were concerned about the dangers of disused wells in China.

RESCUE EFFORTS IN QUESTION

It took over 500 rescuers and 100 excavators more than 100 hours to find the boy's body, according to the local government, leaving many to wonder why it took so long.

After the boy disappeared, rescuers used life-detecting devices, infrared cameras and mechanic rescue arms to try to find him, but all efforts were in vain, Wu said.

As the 30 centimeter-diameter well was too narrow for an adult to enter, rescuers had to dig a 120-meter diameter, funnel-shaped area to try to find the boy, said Pang Zhi, head of a rescue team at the site.

"On four occasions the ground nearly caved-in," he said.

The rescue was hampered by the soft sandy soil, which is prone to collapse, Pang said. Measures were taken to support the shaft during the excavation.

Ma Xiaochun, an associate professor with the faculty of engineering at China University of Geoscience, said that when such accidents happen, rescuers usually contact the victim first, while providing oxygen, lights and food.

"In this case, it was difficult to do so because they were unable to detect the boy, not to mention his physical condition," Ma told Beijing News.

"HUMAN-EATING WELLS"

The case left many worried about China's dry wells, with many netizens coining the phrase "human-eating wells" on Weibo, a Twitter-like service.

According to the boy's grandfather, the well was once used for irrigation but has been out of service for five years, and the well had not been refilled or covered. "There was no warning sign around," he said.

Wu said that the well was dug in the late 1990s, and that there had initially been a cover, but it was somehow removed.

The county government has launched an investigation into all dry wells in Lixian, Wu said.

Thirty-one people have fallen into dry wells in China since 2015, with 80 percent children, according to Beijing News. Forty percent of the victims lost their lives, the newspaper reported.

Northern and eastern regions of China have long experienced water supply issues amid rapid urbanization and growing demand, with underground water dropping to alarming levels in many areas.

As a result, many wells have been abandoned as residents have dug deeper wells searching for more underground water.

In Hebei, about 100,000 wells dried up or had insufficient water as of 2012, according to government figures.

"In China, a lot of rural land has been appropriated for commercial uses, and many farmers have left their wells abandoned," said Zhang Yong, head of China's Blue Sky Rescue, a non-governmental rescue organization.

Zhang said it was urgent to take measures to guard such wells, suggesting a comprehensive inspection of dry wells across the country was needed.

"Abandoned wells should be refilled," he said. "Fences should be established to prevent accidents."