NANNING -- Three more workers injured in a library collapse in south China's Guangxi Zhuang Autonomous Region have died in hospital, bringing the death toll to seven.

The accident occurred on Monday afternoon when the 19-meter-high library building under construction at the Guangxi Medical University collapsed.

At least 14 workers fell from the building. Three died at the scene and another died later in hospital.

Seven other injured workers are receiving treatment, of whom three are in critical condition.

The cause of the collapse is being investigated.