The incident occurred just outside a shopping mall in Cuibai Avenue in Yibin, Sichuan Province with over 5.5 million people. Luckily, authorities confirmed that nobody was hurt but 21 cars certainly were as the 500 square metre sinkhole broke open and swallowed them whole. Provincial TV station SCTV shared the footage online of the very moment that the ground began to crumble. Search and rescue teams searched the area overnight to look for anyone who might have fallen victim to the sinkhole but luckily nobody was found to be injured.An investigation is now underway to find the cause of the sinkhole however local media channel Central China Television says that experts have examined the site previously and claimed it safe for both vehicles and residents. The channel also added that utility providers have taken actions to prevent further incidents. Central China TelevisionWhat is a sinkhole?Sinkholes occur when the ground collapses at the surface level. There are two types of sinkholes. The first is when the roof of an underground cave collapses and exposes the underground cavern and the second is when underground water erodes the earth away to create a chasm. Despite testing for ground stability, it can still be hard to determine just when a sinkhole can occur and sometimes the ground opens up without warning.