On Monday, a day after a landslide buried or toppled 33 buildings at an industrial park in China, at least 91 people were still missing, according to the official Xinhua News Agency, and no deaths had been reported.

An area of more than 650,000 square feet at the manufacturing center in Shenzhen, in Guangdong province, near Hong Kong, was covered in 20 feet of mud, Xinhua reported.

The cause of the landslide was clear: a pile of debris and dirt, left over from construction and piled on a nearby hill, gave way. From the New York Times:

The Weibo page of a local official newspaper, the Shenzhen Tequ Bao, reported that the giant pile of construction debris and earth was illegal and that it had been approved by local officials. Those posts were later deleted.

Just a few miles south of the accident site, in Hong Kong, steep hillsides in populated areas are reinforced by elaborate networks of retaining walls to prevent landslides, which can occur frequently in a region pounded by heavy monsoon rains.

At a news conference, the Associated Press reported, Li Yikan, the deputy secretary general of the Shenzhen city government, said that more than 900 people had been evacuated, and that nearly 1,500 people were involved in the rescue effort.

Photo via Getty Images. Contact the author of this post: brendan.oconnor@gawker.com.