Officials told reporters that preliminary investigations had shown "serious problems exist in the construction, renovation and examination and approval" of the Xinjia Hotel, the official Xinhua News Agency reported.
The hotel in the southeastern city of Quanzhou was being used to quarantine suspected coronavirus patients when it came crashing down Saturday night.
One person previously listed as missing was pulled dead from the rubble on Thursday morning. Forty-two people survived the disaster.
Xinhua quoted Quanzhou's Executive Deputy Mayor Hong Ziqiang as saying that "those responsible for the accident have been taken into custody," but gave no details.
The Ministry of Emergency Management announced Thursday that China's Cabinet, the State Council, has formed a special investigative team to look into the collapse.