Rescuers have successfully lifted out 4 miners who had been trapped for 36 days after a gypsum mine collapsed in Pingyi County, east China's Shandong Province in late December.

Meanwhile, rescue efforts are still in full swing for the 13 trapped miners still listed as missing underground.

Zhang Shuping, mayor of Linyi City, said the search and rescue for the 13 miners remaining underground is ongoing.

"As long as there is a glimpse of hope, the search will continue. Now we are organizing experts to examine the situation and give us some sort of indication concerning the health and condition of the miners and try to figure out new rescue measures."

The four miners rescued on Friday, named as Guan Qingji, Hua Mingxi, Li Qiusheng and Zhao Zhicheng, were brought to the surface one after another in a rescue capsule via a specially drilled access shaft.

They're now receiving treatment at a local hospital. One of them had suffered a fibula fracture on his left side.

Their conditions are said to be stable both physically and psychologically.

However, Cao Qingde, deputy head of the Pingyi People's Hospital, said there still remain a lot of uncertainties since the miners were trapped underground for so long.

"Our hospital will work with experts on both provincial and municipal levels to make a treatment plan for the miners based on the development of their conditions and the test results from the laboratory."

At one point in the rescue operation, the rescuers found out that silts were amassing inside the tunnels underground, gravely endangering the their.

At that time, about 1 million cubic meters of water contained in the goaf were also threatening the miners' confined living space.

Gao Guangwei is an official in charge of emergency resonponse from the State Administration of Work Safety.

He recalled the measures they took to deal with the emergency:

"We finally reached a conclusion that those silt and water came from a neighboring shaft, and we immediately blocked the shaft's bottom by pouring in 100 tons of cement, so as to keep the miners' living space safe and sound."

A total of 29 people were working underground when the gypsum mine collapsed, and 11 people narrowly escaped while one was confirmed dead.

Zhang Shuping believed that changes need to be made in current mining practices.

"One of the lessons we have learned from the accident, is that entirely depending on our current mining resources is unsustainable. We must conduct a comprehensive and thorough investigation into current practices in order to assess what changes need to be made and implement new strategies for non-coal mining. Moreover, those who are responsible for the accident must be held accountable."

The owner of the mine committed suicide by jumping into a flooded shaft in the earlier days of the rescue.

Pingyi County's Party Chief, government head and 2 deputy heads have been sacked following the accident.

Several executives of the mine are under police investigation.