All of the victims were the helicopter's crew, the IRNA news agency said, citing a provincial security official.
According to the news agency ISNA, the helicopter crashed some 19 miles away from the city of Shahr-e Kord several minutes after takeoff.
The helicopter, owned by the National Iranian Drilling Company, was transporting an emergency patient from the Amir Kabir offshore oil platform when it "disappeared half a mile from the oil rig on its way back", Behshahr Governor Khalegh Sajadi stated as quoted by the news agency ISNA.
The Chief of the Red Crescent Society of Chaharmahal and Bakhtiari has stated that five people were killed in an emergency helicopter crash in Chaharmahal and Bakhtiari, the helicopter was on an emergency relief mission.
According to reports, the reason for the crash is still unknown, the helicopter's black box has allegedly not been found yet.
Comment: While the investigation behind the cause of the crash is ongoing, what is clear is that aircraft crashes have been on the rise in recent years: