Let's have three cheers for the Chinese 'don't give a damn' attitude about regulations and safety.

It was not conventional explosives but looks a lot like a neutron bomb. None of the cars were moved or shifted by conventional explosive force. A neutron bomb however can emit a lot of radiation that gets absorbed by metals - steel - heating things like cars. Glass can absorb UV and if the bomb emitted a lot of short wave UV that probably got absorbed by all the glass and it melted or shattered. Any plastic interlayer included for collision shock fragmenting simply evaporated. Tire rubber might melt and blow out from contact with superheated rims but also any steel belt in the tires would absorb energy and then heat and melt them from inside. How on earth did the Chinese accidently deploy a neutron bomb though?