Chinese President Xi Jinping has ordered all-out efforts to rescue the trapped and injured people.
Five people have been rescued and admitted to nearby hospitals.
The six-story building, which has a floor area of about 700 square meters, toppled at noon on Friday in Changsha city’s Wangcheng district, state-run China Global Television Network reported.
Rescuers were searching for more survivors as 39 people were reported missing. At least 23 have been trapped.
The owner of the building has been detained.
Huang Ming, minister of emergency management, in a video conference on Saturday called for an inspection of work safety to prevent further accidents.
“Related departments should launch a crackdown on illegal and irregular building activities such as unauthorised construction and unauthorised alteration of the main structure to prevent collapses and other similar accidents,” Huang said.
On Saturday, Chinese State Councilor Wang Yong led a team to Changsha to guide rescue and emergency response.