NANNING - Chances of survival are slim for two workers trapped in a collapsed tunnel in South China's Guangxi Zhuang autonomous region, rescuers said on Tuesday.

No signs of life have been detected around the tunnel, said Yang Lichuang, head of the firefighting department of the province's city of Hechi.

The collapsed tunnel was part of a highway construction project in the city's Du'an Yao autonomous county.

The accident happened at 12:10 pm Monday, when more than 10 construction workers were working inside the tunnel. Most of the workers managed to escape.

Deng Huanping was the first worker to realize what was happening.

"I was standing on some scaffolding with eight others when stones began falling off of the scaffolding," Deng said.

Wei Changyi, a 26-year-old worker, is one of the two trapped workers. His father, Wei Daixi, is a road construction worker as well, although he did not work with his son on this particular project.

"I have been doing this work for many years. I never expected that such a tragedy could happen to us," he said.

Rescuers are using forklifts to clear the tunnel and search for the trapped workers.