Rescuers Dig For Survivors After Massive Mudslide in China's Shenzhen

The disaster came when a huge pile of unwanted earth collapsed, engulfing 33 buildings.

A mudslide triggers a gas pipeline explosion in Shenzhen, southeastern China's Guangdong province, Dec. 20, 2015.

Dozens of people remained missing on Monday following Sunday's devastating mudslide in the southern Chinese city of Shenzhen, official media reported.

The disaster saw streets and buildings in the Hengtaiyu district of the city engulfed in mud 10 meters (33 feet) deep, after a massive pile of construction waste collapsed.

The mudslide, which prompted the evacuation of around 1,500 residents, came after experts warned local officials that the pile was unstable.

Video shot by eyewitnesses showed mud and dust shooting up into the air as it hit tall buildings in its path amid sounds of shrieking and car horns, before covering everything in its path in a sea of red mud.

"The whole thing has collapsed," one eyewitness comments on the video. "I don't know how many people have died; the whole thing has come down."

An eyewitness surnamed Chen said some of his colleagues have been missing since the mudslide struck.

"There are some workers we can't get in touch with, so I'm pretty sure that the death toll is going to rise," Chen said.

"The Liuxi industrial park has completely disappeared, and there were more than 100 people putting in overtime [at the factory] on Sunday," he said.

The area around Hengtaiyu's Guangming New District was being combed by some 3,000 rescue workers and excavation teams, state news agency Xinhua reported on Monday.

It said more than 90 people remained missing on Monday morning, while dozens more, including children, had been taken to hospital.

Of the 33 buildings buried, 14 were factory buildings, while office buildings and dormitories were also under the mudslide, Xinhua quoted deputy Shenzhen mayor Liu Qingsheng as saying.

"We will do everything we can to make use of the 72-hour survival window in our rescue work," officials said in a statement on the Guangming New District's official website.

"We will take our responsibilities very seriously," it said.

It said 78 excavators had been drafted in, and were digging through the mud on a grid system with the help of rescue teams.

Evacuated local residents were offered temporary shelter in the Guangming District Sports Center, it said.

Gas pipeline explosion

The mudslide also triggered a gas pipeline explosion, rupturing a 400-meter (1,312-foot) section of China's East-West gas pipeline.

A regional source told RFA that the mud had been piled up by successive hill-leveling operations as the area moved from countryside to rapidly-urbanizing industrial zone hungry for land.

"They basically had all this earth left over from digging away at the little hills and they had no use for it, so they just left it there in a big heap," the source, who gave only a surname Luo, said.

"Also, Shenzhen had recent rainfall, so there was an issue with subsidence," he said. "The pile wasn't very big, but it was about 100 meters [328 feet] high."

The Hongao construction waste tip had been flagged by local authorities as early as August 2013 for "illegal dumping of construction waste," documents on the Guangming New District official website showed.

And in April, the authorities stopped 13 trucks for illegally dumping construction waste in Guangming district, the website said.

According to Chen, there has been a “continual” stream of trucks dumping earth at the Hongao site since he arrived in the area earlier this year.

"It just got piled higher and higher, up to more than 100 meters, and nobody did anything about it," he said. "The trucks just kept on coming."

Police had thrown a tight security cordon around the rescue site on Monday, according to Shenzhen-based charity worker Zhang Zhiru.

"We went to the scene on Sunday, but we couldn't get in because they have sealed off the entire area," Zhang told RFA. "The only information we can get is from the online media, because the rescue workers and officials at the site won't talk to anyone."

"The local government is responsible ... but it's likely that they will try to cover some things up."

Hong Kong's South China Morning Post newspaper cited one Guangming online document as saying that the Hongao site had been ordered to close in July.

But a link on the site dated in July, and related to Hongao's operating license, returned the message "Sorry, the article you are looking for doesn't exist" on Monday.

Reported by Ka Pa and Dai Weisen for RFA's Cantonese Service, and by Xin Lin and Gao Shan for the Mandarin Service. Translated and written in English by Luisetta Mudie.