KUNMING - A new cave-in has hampered rescue efforts for eight workers trapped in a tunnel that collapsed in Southwest China's Yunnan province on Thursday, rescuers said Friday.

The second cave-in occurred on Friday as a result of water seeping into the tunnel after heavy rains struck the accident site early Friday morning, according to the local rescue headquarters.

The rescuers have not been able to contact the trapped workers since the first collapse occurred, according to the headquarters.

The collapsed section of the tunnel, estimated to be 15 meters in length, is located about 460 meters away from the tunnel's entrance, rescuers said, adding that ventilation facilities and water pipelines in the tunnel remain undamaged.

Rescuers have been feverishly working to dig through the caved-in section of the tunnel, hoping to send food to the trapped miners. Rescuers may use explosives to open up the tunnel more quickly, according to the headquarters.

Thursday's cave-in occurred in a tunnel under construction on National Highway 214, which links the province's Shangri-La county with Deqen county.