A spokesperson from the Police Media Unit told Xinhua that the accident occurred when five employees of a gem mining company were at work searching for gems.

Four of the employees were killed on the spot when the mine collapsed while the injured was rushed to the Ratnapura Hospital for treatment.

Local police have launched an investigation into the incident.

Ratnapura is known as the "City of Gems" in Sri Lanka and it is the center of a long-established industry of precious stone mining including the country's famous rubies, sapphires, and other gems.

(Xinhua)