The fact is when underground cables are damaged it would caused dangerous to people. People can be killed and injured by an electric shock, electric arc (causing an explosion) and flames. The results from these injuries are severe burns to hands, face and body, even if protective clothing is being worn as shown in the pictures.
“Avoiding danger from underground services” (http://www.hse.gov.uk/) outlines unseen dangers arising from working near underground services – with guidance advice on risk reduction, especially concerning ground penetration or below surface operations.
Courtesy of pictures from google image