A section of an ancient city wall ruins in northwest China's Xi'an City collapsed on August 8. Four people sustained minor injuries and several cars were damaged in the incident.

Local authorities announced that the collapse was caused by the recent heavy rainfall. About 20 meters of the wall collapsed in just a few seconds.

According to the expert analysis, the cultural relic itself has not been damaged, and the cultural relics department is implementing emergency protection measures in the area. 

This section that collapsed belongs to Ming Qin King city wall, which was built in 1374. It's the only existing soil city wall in Xi'an, which is partly why it collapsed: soil can easily swell and move when it absorbs lots of rainwater. 

The local community has been aware of the dangers of the ancient city wall for a long time. A rain-proof canopy was laid at the top, and a fence was added at the bottom. Between 2007 and 2011, the remaining walls of the palace of the Qin king of Ming dynasty (1368-1644) were also reinforced. 

(Cover image: The ancient city wall ruins that collapsed Saturday. /CFP)