The search and rescue operation was ongoing on Tuesday at the site of the disaster, which left a gaping hole in a dense streetscape.
Over the weekend, state media showed firefighters backed by heavy machinery trying to cut through mangled metal and concrete.
At least 14 were people still known to be trapped in the rubble while no contact had been established with 39 others.
Nine people, including the building's owner and a team of safety inspectors, have been detained in connection with the accident, according to Changsha police.
Authorities have alleged that surveyors falsified a safety audit of the building.
President Xi Jinping has ordered a thorough investigation into the cause of the collapse, state media reported.
