KUNMING, July 14 -- An estimated 14 workers were trapped after part of a railway tunnel collapsed in southwest China's Yunnan Province Monday, the local government said in a press release.

The accident happened at around 4 p.m. in Funing County of Zhuang and Miao Autonomous Prefecture of Wenshan.

The tunnel, known as Funing No. 1 tunnel, was on a pivotal railway linking Yunnan with south China's Guangxi Zhuang Autonomous Region.

The cause of the accident and the exact number of casualties were still under investigation.