Four workers were injured and two others are missing when a railway-highway bridge under construction collapsed Monday in southwest China's Guizhou Province, rescuers said.

The accident happened at around 7 a.m., said a spokesman with the emergency rescue headquarters in Guiyang, the provincial capital.

As of midday, the rescuers were still searching for the two missing workers, he said.

The four injured were taken to hospital. Two of them were described as seriously injured, but none of the injuries were thought to be life-threatening, the spokesman said quoting hospital sources.

The bridge under construction was part of a cloverleaf junction where a railway linking Shanghai with Kunming, capital of the neighboring Yunnan Province, meets an urban highway in Guiyang.

The bridge was being built by the Guiyang section of Chengdu Railway Bureau in Sichuan, and the main contractor is China Railway Construction Corp. Ltd..

Work safety officials are investigating the cause of the accident.

(Xinhua News Agency August 31, 2009)