A helicopter carrying personnel working for Saudi Aramco crashed Sunday morning near the eastern Saudi city of Ras Tanura, leaving all 14 people on board dead, Saudi state media reported.

The aircraft went down at approximately 6 a.m. local time. Officials said every passenger aboard was a Saudi citizen.

Authorities have not determined what caused the crash. An investigation is underway to establish the circumstances surrounding the accident, according to the Saudi Ministry of Energy.

The helicopter was operating in Ras Tanura, home to one of the world's largest oil export terminals and a critical hub for Saudi Arabia's petroleum industry. While the crash occurred in the country's key energy-producing region, officials have not indicated that the incident affected oil operations.