The landslide struck Shenzhen's Liuxi Industrial Park in the city's northwestern Guangming New District in the morning, said the official Xinhua news agency, citing rescuers.
Four people have been rescued from the debris, with three sustaining minor injuries, it said.
As of 0900 GMT, rescuers had evacuated more than 900 people from the site, said Xinhua.
Xinhua had earlier said at least 41 people were missing, with seven people rescued and one suffering minor injuries.