Yesterday's fire broke out in the Shahr-e-Kord prison killing 11 prisoners through suffocation before being brought under control, Abdullah Mousavi, a judiciary official, told the state news agency IRNA.
Iran's head penal official, Asghar Jahangir said the fire was caused by arson and an investigation was underway.
"Cameras have recorded when the fire broke out in the prison and it was started by an individual intentionally," he told the semi-official ISNA news agency. "He survived and has been detected."
Iranian news outlets said several people were also injured in the incident.