Four men aged between 34 and 50 died in a cave beneath the city of Loutraki in Greece, reportedly during a search for treasure, local outlet Loutraki365 reported.
"The cause of death is still unknown. The most likely scenario investigated by the authorities is that the four men were searching for treasure and tragically died while attempting to blow some kind of an explosive device. Some of them had wires in their hands", the outlet says.
The incident was reported by a woman, who turned out to be the wife of one of the victims.
Firefighters recovered the bodies early in the morning, while the operation involved 21 personnel and five vehicles.