KUNMING -?Nine construction workers who have been trapped in a collapsed railway tunnel in southwest China's Yunnan Province for one day were confirmed alive Friday, local authorities said.

The tunnel in the Xishuangbanna Dai Autonomous Prefecture they were working on collapsed at about 10:20 a.m. Thursday.

After digging a small hole through the rocks, rescuers managed to contact the workers with the help of a thin pipe and confirmed that the workers were all alive at 11:25 a.m. Friday, said the information office of the prefecture government.

Rescuers were racing against time to reach the workers while installing a mobile phone signal amplifier to help them keep contact.

The tunnel is part of a railway that connects Yuxi and Mohan in Yunnan.