According to the police, the four were busy harvesting grapes on the farm Sador in Louisvale when they were hit by the lightning. They were declared dead on the scene.
Police spokesperson Colonel Mashay Gamieldien said about five other farmworkers were also transported to a local hospital to be treated for shock.
She added that those who were taken to hospital were not injured.
“The identities of the deceased cannot be released yet as the police and family are in the process of formally identifying the bodies,” Gamieldien said.
She said an inquest case was being investigated.
On Sunday in Germiston, Johannesburg, one man died and a teenage boy was injured when they were struck by lightning while they were sitting under a tree.