TAIYUAN -- An outer wall of a library in North China's Shanxi province collapsed Saturday afternoon, killing three people and injuring another, local sources said.

The collapse occurred at around 3 pm at Shanxi Provincial Library in Taiyuan city, according to the provincial fire brigade. The collapsed wall section was a temporary construction.

A woman was seriously injured but in stable condition, a local hospital said.

An investigation into the cause of the collapse is under way.