At least nine people have been arrested following the collapse of a building in the city of Changsha, police in central China said on Sunday.

Rescue operations entered a third day after the multi-purpose building  partially collapsed in China's Hunan province around noon local time on Friday.

As of Sunday, about 20 people remained trapped in the building, according to Mayor Zheng Jianxin. Another 39 remain uncontactable following the accident.

Later in the day, state media reported that a sixth survivor, a woman, had been pulled from the rubble.

Footage from the scene showed rescue crews digging through debris and sniffer dogs searching for signs of life.

Five people have been rescued so far and taken to the hospital, but are in stable condition, officials said at a press conference on Saturday.

What do we know about the arrests?

Changsha police said the building's owner and three people responsible for construction and design were detained over the collapse. In a post on the Chinese social media platform Weibo, police said they were suspected of "major responsibility for an accident."

Another five people who work at a private building inspection firm were also detained on suspicion of providing "a false safety report."

The building contained a hotel, movie theater and apartments.

President Xi: Rescue people 'at all costs'

President Xi Jinping gave instructions to rescue people stuck in the building "at all costs."

State broadcaster CCTV reported that people living in the building had made structural changes to the premises, while the exact cause of the collapse is still being investigated.

Authorities in China often blame such disasters on a lack of adherence to safety standards, such as the illegal addition of extra floors.

rs, jsi, tj/wd (AP, AFP)