Five workers are feared dead after being trapped for more than 20 hours in a subsea pipeline that flooded off south China's Hainan Province.

"The possibility of their survival is almost zero," said Lin Beichuan, secretary general of the government of the provincial capital Haikou, at a press conference on Thursday afternoon.

The pipeline of a sewage treatment plant and a deep shaft connected to the pipeline filled with seawater around 7:45 PM on Wednesday. Six workers were there at the time, but only one managed to escape.

The survivor, Gao Peizhi, was in the pipeline and 400 meters away from the shaft when it flooded. He heard an unusual sound and immediately rushed to the shaft and managed to escape, according to Bao Yiguo, an investigator with the local work safety bureau.

Gao met one of the trapped workers about 200 meters away from the shaft. Gao told him to run, but the worker failed to escape.

The five people still trapped were between 23 and 47 years old. They were from villages in Gaochun County, Jiangsu Province, Bao said.

Lin, the Haikou government secretary general, said families of the five workers have been notified and rescuers were still trying to find the workers.

Six divers were assisting in the search.

Li Quan, a designer of the pipeline and the shaft, said the shaft was more than 20 meters deep and the pipeline connected to the bottom of the shaft. The pipeline is 1.6 meters in diameter and 1,350 meters long.

(Xinhua News Agency June 12, 2009)