A 24-year-old woman trapped for more than 22 hours in the rubble of a residential building that collapsed was saved on Monday.

But her roommate, a 21-year-old woman, was killed after the building fell down on Sunday in Ningbo city in East China's Zhejiang province. Residents had earlier been told to evacuate the building after large cracks appeared.

The two women, who lived on the second floor, could not be reached by phone on Sunday morning when the evacuation order was given.

Yang Xuefeng, an official at Ningbo Fire Station, said they kept calling after the collapse and finally a woman answered, but it was difficult to tell what she was saying.

The survivor's boyfriend, who rushed to the scene on Sunday night, told China News Service he managed to call her and kept encouraging her to hold on. Local media said the woman is conscious and can answer doctors' questions, but she is suffering from trauma.

She was not located until 6:50 am on Monday, 19 hours after the building collapsed.

The survivor was pulled from the debris at 10:40 am. She was taken to a hospital and her life is not in danger, said Li Guohong, deputy district chief of Ningbo's Jiangdong district, where the building was located.

"The search-and-rescue work was hard because we couldn't use large machinery due to the small working area — the work was mainly done by hand," Li said.

The survivor's roommate, a woman from Anhui province who was found in the rubble and rescued died in a hospital on Sunday night around 7:30 pm, two and half hours after being discovered.

"Residents of nearby buildings ran away before Sunday night after they witnessed what happened," said Jiang Kejie who lives in a nearby block and visited the collapse scene twice after the incident.

Some 150 rooms in seven hotels were used as temporary shelters for 256 families affected by the collapse, according to local community workers.

Forty-three people lived in the six-story building, built in 1989 and which collapsed shortly after noon while some residents were removing their belongings after receiving the evacuation notice from the neighborhood committee.

Xia Haiming, chief engineer of Ningbo housing and urban-rural development Committee, said on Monday a preliminary investigation showed the building did not have a damp-proof coating at its base because that was not requested when it was built.

Xia said the load-bearing walls were severely weathered due to the climate and this had contributed to the collapse.

Pang Jianghua, an expert in housing structure from estate developer Shanghai Greenland Group, said the quality of housing built during the 1980s and 1990s was not that good due to low design standards and limited construction materials.

Residents living nearby said they had been complaining about problems, including subsidence and cracks, for more than 2 years.

The local government in Ningbo launched a dangerous buildings hotline on Monday and issued an emergency notice stating that safety inspections will be carried out on buildings in the city that are more than 20 years old.

Cao Meili and Tang Yaochang contributed to this story.

Contact the writer at shiyingying@chinadaily.com.cn