NANNING -- The death toll of a highway traffic accident in south China's Guangxi Zhuang Autonomous Region has risen to four, authorities said Wednesday.

Three people died at the scene and a further person died in hospital. Another 50 people injured are being treated in hospital.

The accident occurred at 1:50 Wednesday morning on a section of the Guangzhou-Kunming Highway in Baise City, when a coach bus hit a freight truck. The bus was carrying 54 people, including two drivers.

An investigation is underway.