Peter Chaparanganda, Deputy spokesperson for the prison services, made the disclosure on Tuesday, saying the incident occurred on Friday at the jail in the town of Hwange.
The inmates, he said, were inside the prison yard when the lightning struck at around 11:30.
The group was taken to the hospital where four of them were reported to be serious while the other nine were reported to be stable, Chaparanganda added.
Lightening accompanying summer thunderstorms is a common occurrence and responsible for several deaths each year in Zimbabwe.
