Landslide hit an industrial park in Shenzhen, Guangdong province, China Sunday December 20, 2015

At least 91 people were missing after a huge mound of mud and construction waste collapsed at a business park in southern China and buried 33 buildings in the country's latest industrial disaster.

Premier Li Keqiang ordered an official investigation into Sunday's landslide in the southern boomtown of Shenzhen, just across the border from Hong Kong, which comes four months after huge chemical blasts at the northern port of Tianjin killed more than 160 people.

The mudslide smashed into multi-storey buildings at the Hengtaiyu industrial park in the city's northwestern Guangming New District, toppling them in collisions that sent rivers of earth skyward

An aerial view shows the site of a landslide at an industrial park in Shenzhen, Guangdong province, China, December 20, 2015

Rescuers search for survivors in a collapsed building following a landslide in Shenzhen, in south China's Guangdong province, Sunday, Dec. 20, 2015

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Rescuers search for survivors among damaged buildings buried at and around an industrial park in Shenzhen

Rescuers search for survivors at the site of the landslide in Shenzhen, which left an area of about 200,000 square feet covered with soil.

Firefighters search for survivors among the rubble of collapsed buildings after a landslide hit an industrial park in Shenzhen, Guangdong province, China December 21, 2015

A general view shows buildings covered by dirt and mud after a landslide in Shenzhen.

Evacuated people rest at a makeshift shelter located at a sports center in Shenzhen, south China's Guangdong Province, Dec. 21, 2015.