The building in Changsha city, Hunan province – which housed a hotel, apartments and a cinema – caved in Friday afternoon, leaving a gaping hole in the dense streetscape.

City officials said Saturday five survivors had been pulled out of the structure, leaving 18 still trapped. A further 39 could not be contacted after the incident.

After 50 hours of rescue efforts, a woman – the sixth survivor – was pulled out from the rubble Sunday, state broadcaster CCTV reported, showing footage of firefighters loading a person covered in dust onto a gurney.

Changsha police said nine people – including the building’s owner and a team of safety inspectors – were detained Sunday in connection to the accident. They alleged that surveyors had falsified a safety audit of the building.

No cause for the disaster has yet been given by authorities.

Changsha’s mayor earlier vowed to “spare no effort” in their search for the people still trapped.

“We will seize the golden 72 hours for rescue and try our best to search for the trapped people,” mayor Zheng Jianxin said in news briefing Saturday.

He added that over 700 first responders had been dispatched to the scene.

State media showed firefighters – backed by a digger – cutting through a morass of metal and sheets of concrete, while rescuers shouted into the tower of debris to communicate with any survivors.

A crowd gathered as chains of rescuers removed pieces of brick by hand, allowing experts a deeper look into the wreckage.

Some of the injured were rushed away on stretchers, while sniffer dogs combed the area for further signs of life.

President Xi Jinping on Saturday called for a search “at all cost” and ordered a thorough investigation into the cause of the collapse, state media reported.

A top Communist Party official was dispatched to the scene – an indication of the severity of the disaster.

China’s minister of emergency management Huang Ming urged officials to “thoroughly eliminate all kinds of hidden safety risks” in a Saturday meeting.

Building collapses are not uncommon in China, due to weak safety and construction standards as well as corruption among officials tasked with enforcement.

In January, an explosion triggered by a suspected gas leak brought down a building in the city of Chongqing, killing at least 16 people.